VYSIS INC, S-1/A, 1998-01-06

VYSIS INC
S-1/A, 1998-01-06
IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES

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AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JANUARY 6, 1998

REGISTRATION NO. 333-38109
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
--------------------------

AMENDMENT NO. 2 TO
FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933
--------------------------

VYSIS, INC.

(Exact name of registrant as specified in its charter)

<TABLE>
<S> <C> <C>
DELAWARE 2835 36-3803405
(State or other jurisdiction (Primary Standard Industrial (I.R.S. Employer
of Classification Code Number) Identification
incorporation or organization) Number)
</TABLE>

3100 WOODCREEK DRIVE, DOWNERS GROVE, ILLINOIS 60515

(630) 271-7000

(Address, including zip code, and telephone number, including
area code, of registrant's principal executive offices)

JOHN L. BISHOP
PRESIDENT AND CHIEF EXECUTIVE OFFICER
VYSIS, INC.
3100 WOODCREEK DRIVE, DOWNERS GROVE, ILLINOIS 60515

(630) 271-7000

(Name, address, including zip code, and telephone number, including area code,
of agent for service)
--------------------------

COPIES TO:

DAVID A. SCHUETTE WILLIAM J. GRANT, JR.
Mayer, Brown & Platt Willkie Farr & Gallagher
190 S. LaSalle Street One Citicorp Center
Chicago, Illinois 60603 153 East 53rd Street
(312) 782-0600 New York, New York 10022
(212) 821-8000

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APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:
AS SOON AS PRACTICABLE AFTER THE EFFECTIVE DATE OF THIS REGISTRATION STATEMENT.
--------------------------

If any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, check the following box: / /

If this Form is filed to register additional securities for an offering
pursuant to rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. / /

If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. / /

If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box: / /
--------------------------

CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
PROPOSED MAXIMUM PROPOSED MAXIMUM
TITLE OF EACH CLASS OF AMOUNT TO OFFERING PRICE AGGREGATE AMOUNT OF
SECURITIES TO BE REGISTERED BE REGISTERED(1) PER SHARE(2) OFFERING PRICE(2) REGISTRATION FEE
<S> <C> <C> <C> <C>
Common Stock, $0.001 par value.............. 4,025,000 $15.00 $60,375,000 $18,296(3)
</TABLE>

(1) Includes 525,000 shares which the Underwriters have the option to purchase
to cover over-allotments, if any. See "Underwriting."

(2) Estimated solely for purposes of calculating the registration fee pursuant
to Rule 457 under the Securities Act.

(3) Previously Paid.

THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF
THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE SECURITIES AND EXCHANGE COMMISSION, ACTING
PURSUANT TO SAID SECTION 8(A), MAY DETERMINE.

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- --------------------------------------------------------------------------------
<PAGE>

SUBJECT TO COMPLETION, DATED JANUARY 6, 1998

INFORMATION CONTAINED HEREIN IS SUBJECT TO COMPLETION OR AMENDMENT. A
REGISTRATION STATEMENT RELATING TO THESE SECURITIES HAS BEEN FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION. THESE SECURITIES MAY NOT BE SOLD NOR MAY
OFFERS TO BUY BE ACCEPTED PRIOR TO THE TIME THE REGISTRATION STATEMENT BECOMES
EFFECTIVE. THIS PROSPECTUS SHALL NOT CONSTITUTE AN OFFER TO SELL OR THE
SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE SECURITIES
IN ANY STATE IN WHICH SUCH OFFER, SOLICITATION OR SALE WOULD BE UNLAWFUL PRIOR
TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS OF ANY SUCH STATE.
<PAGE>
PROSPECTUS

3,500,000 SHARES

[LOGO]

COMMON STOCK

All of the shares of Common Stock offered hereby are being sold by Vysis,
Inc., a Delaware corporation ("Vysis" or the "Company"). Prior to this offering,
there has been no public market for the Common Stock of the Company. It is
currently estimated that the initial public offering price will be between
$13.00 and $15.00 per share. See "Underwriting" for a discussion of the factors
to be considered in determining the initial public offering price. The Common
Stock has been approved for quotation on the Nasdaq Stock Market under the
symbol "VYSI."

THE COMMON STOCK OFFERED HEREBY INVOLVES A HIGH DEGREE OF RISK.
SEE "RISK FACTORS" BEGINNING ON PAGE 8.
---------------------
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION, NOR HAS THE
SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES
COMMISSION PASSED UPON THE ACCURACY OR ADEQUACY OF
THIS PROSPECTUS. ANY REPRESENTATION TO THE
CONTRARY IS A CRIMINAL OFFENSE.

<TABLE>
<CAPTION>
UNDERWRITING
DISCOUNTS AND PROCEEDS TO
PRICE TO PUBLIC COMMISSIONS(1) COMPANY(2)
<S> <C> <C> <C>
Per Share................................. $ $ $
Total(3).................................. $ $ $
</TABLE>

(1) The Company has agreed to indemnify the Underwriters against certain
liabilities, including liabilities under the Securities Act of 1933, as
amended. See "Underwriting."

(2) Before deducting expenses payable by the Company, estimated at $1,200,000.

(3) The Company has granted to the several Underwriters a 30-day option to
purchase up to 525,000 additional shares of Common Stock solely to cover
over-allotments, if any. If all such shares are purchased, the total Price
to Public, Underwriting Discounts and Commissions and Proceeds to Company
will be $ , $ and $ , respectively. See
"Underwriting."

------------------------

The shares are being offered by the several Underwriters when, as and if
delivered to and accepted by the Underwriters, and subject to various prior
conditions, including the right to reject orders in whole or in part. It is
expected that delivery of share certificates will be made against payment
therefor at the offices of Furman Selz LLC in New York, New York on or about
, 1998.

FURMAN SELZ

DEUTSCHE MORGAN GRENFELL

EVEREN SECURITIES, INC.
---------------

The date of this Prospectus is , 1998.

<PAGE>
INSIDE FRONT COVER

(GRAPHICS)

A two-color collage of four photographs arranged within a box and entitled
"Genomic Disease Management Products." Overlaid in the center of the box is the
term "Genetic Assessment." The picture in the upper left-hand corner of the box
is a young girl being examined by a physician with a stethoscope. The picture in
the upper right-hand corner of the box is that of an unborn fetus in utero. The
picture in the lower left-hand corner of the box is an elderly man dressed in a
hospital robe. The picture in the lower right-hand corner of the box is a woman
performing a self breast exam to screen for breast cancer. At the bottom of the
page is the Company's logo and the words "Managing Disease With Molecular
Techniques."

CERTAIN PERSONS PARTICIPATING IN THIS OFFERING MAY ENGAGE IN TRANSACTIONS
THAT STABILIZE, MAINTAIN, OR OTHERWISE AFFECT THE PRICE OF THE COMMON STOCK,
INCLUDING BY ENTERING STABILIZING BIDS OR EFFECTING SYNDICATE COVERING
TRANSACTIONS. FOR A DESCRIPTION OF THESE ACTIVITIES, SEE "UNDERWRITING."
<PAGE>
GATEFOLD, 2 PAGE SPREAD

(GRAPHICS)

A color spread of seven photographs entitled "Product Platforms for Genomic
Disease Management." The photographs are grouped into three categories. The
first category has the heading entitled "FISH System" and is placed on the top
two-thirds of the left-hand page and contains three photographs. One of the
three photographs is a computer workstation with a woman looking at the computer
screen and has the caption "Quips-TM- FISH Workstation." The second photograph
is a cell with multiple colored spots (signals) and has the caption
"MultiVysion-TM- PGT 5-color FISH probe panel for preimplantation genetic
testing for chromosomes 13, 18, 21, X and Y (Marketed on a Research Use Only
basis)." The third and last photograph in this group shows multiple chromosomes
each represented in a different color with the caption "Quips mFISH System for
multi-color fluorescence probe imaging and analysis (Quips FISH Workstation and
mFISH software are marketed on a Research Use Only basis)."

The second category of photographs positioned on the bottom third of the
left-hand page contains two photographs and is entitled "gCGH-TM- Array*." One
of the photographs has the caption "gCGH Array for simultaneous assessment of
multiple genes" and is a drawing of the gCGH disposable device, a blow-up of an
example array and a mock report showing which genes in the example array are
amplified or deleted. The second photograph in this group is a color image of an
actual hybridized array and has the caption "Hybridized gCGH Array."

The third category of photographs positioned on the right-hand page is
entitled "Molecular Lawn-TM-*" and contains two photographs. One of the
photographs is a drawing of the Molecular Lawn amplification reaction and has
the caption "Molecular Lawn Amplification Reaction." The second photograph is a
drawing of a prototype Molecular Lawn device with the caption "Molecular Lawn
Disposable Test Device."

A DNA double helix weaves throughout the three categories of platforms. The
Company's logo and the words "Managing Disease With Molecular Techniques" are
placed at the bottom of the right-hand page.

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*Product platform in Research and Development. No products utilizing this
platform are currently marketed by the Company and no assurances can be given
that the necessary FDA or other applicable regulatory approvals for diagnostic
use of such products will be obtained.

<PAGE>
PROSPECTUS SUMMARY

THE FOLLOWING SUMMARY IS QUALIFIED IN ITS ENTIRETY BY THE MORE DETAILED
INFORMATION, INCLUDING "RISK FACTORS," AND CONSOLIDATED FINANCIAL STATEMENTS,
INCLUDING THE NOTES THERETO, APPEARING ELSEWHERE IN THIS PROSPECTUS. UNLESS
OTHERWISE INDICATED, THE INFORMATION IN THIS PROSPECTUS (I) REFLECTS A
1-FOR-1.37 REVERSE STOCK SPLIT EFFECTED ON NOVEMBER 21, 1997, (II) REFLECTS THE
CONVERSION OF ALL OUTSTANDING SHARES OF PREFERRED STOCK OF THE COMPANY INTO
COMMON STOCK UPON COMPLETION OF THIS OFFERING AND (III) ASSUMES THAT THE
UNDERWRITERS' OVER-ALLOTMENT OPTION IS NOT EXERCISED. EXCEPT FOR HISTORICAL
INFORMATION CONTAINED HEREIN, THIS PROSPECTUS CONTAINS FORWARD LOOKING
STATEMENTS THAT INVOLVE RISKS AND UNCERTAINTIES, SUCH AS STATEMENTS OF THE
COMPANY'S PLANS, OBJECTIVES, EXPECTATIONS AND INTENTIONS. THE CAUTIONARY
STATEMENTS MADE IN THIS PROSPECTUS SHOULD BE READ AS BEING APPLICABLE TO ALL
RELATED FORWARD LOOKING STATEMENTS WHEREVER THEY APPEAR IN THIS PROSPECTUS. THE
COMPANY'S ACTUAL RESULTS COULD DIFFER MATERIALLY FROM THOSE DISCUSSED HEREIN.
UNLESS THE CONTEXT OTHERWISE REQUIRES, ALL REFERENCES TO THE "COMPANY" AND
"VYSIS" SHALL MEAN VYSIS, INC., A DELAWARE CORPORATION, AND ITS PREDECESSORS AND
SUBSIDIARIES, AND ALL REFERENCES TO "AMOCO" SHALL MEAN AMOCO CORPORATION, AN
INDIANA CORPORATION, AND ITS WHOLLY OWNED SUBSIDIARY, AMOCO TECHNOLOGY COMPANY,
A DELAWARE CORPORATION. A GLOSSARY OF TECHNICAL TERMS USED IN THIS PROSPECTUS IS
ANNEXED HERETO.

GENOMIC DISEASE MANAGEMENT

Genetic abnormalities are a fundamental source of human disease. Genetic
based diseases and disorders include cancer, birth defects, mental retardation,
coronary artery disease, autoimmune diseases and diabetes. Genomic Disease
Management is an emerging field that seeks to develop new genetic tests based on
correlations between genetic abnormalities and disease. Genomic Disease
Management products, by providing new information not currently available
through existing methods, enable physicians to diagnose disease more quickly and
accurately, to determine the most appropriate treatment and to monitor disease
progression and recurrence during therapy. Genomic Disease Management products
also enable the detection of disease at the very early or developing stages when
treatment is likely to be most effective. In addition, Genomic Disease
Management products allow physicians to identify genetic predisposition to
disease well before the disease is manifested, thus enabling early intervention
either through lifestyle changes or preventive therapy.

THE COMPANY

Vysis is a leading Genomic Disease Management company that develops,
commercializes and markets clinical products that provide information critical
to the evaluation and management of cancer, prenatal disorders and other genetic
diseases. The Company has assembled a management team experienced in developing,
commercializing and marketing DNA based diagnostic products and associated
genetic workstations. The Company was the first to obtain Food and Drug
Administration ("FDA") clearance for a genomic product using fluorescence IN
SITU hybridization ("FISH"). Vysis currently markets five FDA cleared clinical
products in addition to distributing over 240 research products through its
direct sales operations in the United States and Europe and a worldwide
distribution network covering 28 countries. It has an installed base of over 320
proprietary genetic workstations at 224 laboratories in 18 countries. The
Company has a pipeline of nine clinical products under development and an
expanding list of clinical product leads based upon its collaborations with
leading medical research institutions which include the University of
California, San Francisco, the Mayo Clinic, St. Jude Children's Research
Hospital, the University of Chicago and the Reproductive Genetics Institute. The
Company's revenues have grown from $5.4 million in 1994 to $13.2 million in
1996. The Company's revenues for the first nine months of 1997 were $12.2
million compared to $9.0 million for the first nine months of 1996. The Company
had net losses of $18.7 million, $17.7 million, and $18.2 million for the years
ended December 31, 1994, 1995 and 1996, respectively. The net loss for the first
nine months of 1996 as compared to 1997 has declined from $13.8 million to $11.5
million.

3
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The Company's business represents the consolidation of multiple research
units and programs of Amoco. Over the past ten years, Amoco has invested over
$80 million to fund Vysis' research and development in nucleic acid technologies
and related business operations. As a result of this investment, Vysis has
compiled a broad portfolio of intellectual property and expertise, which forms
the basis of its core technologies. Vysis owns or has an exclusive license to 92
issued United States patents or allowed United States patent applications and 69
pending United States patent applications that protect its core technologies,
diagnostic platforms and genetic targets. Upon completion of this offering,
Amoco will beneficially own approximately 63% of the Company's outstanding
Common Stock.

The Company is currently focusing its cancer product development efforts on
leukemia, breast, bladder, prostate and cervical cancers. The American Cancer
Society estimates that approximately 1.4 million people in the United States
will be diagnosed with some form of cancer in 1997. Approximately 27,600
patients developed some form of leukemia in 1996. Breast cancer is the second
leading cause of death from cancer among women aged 35 to 54, and prostate
cancer is the second leading cause of death from cancer in men. The American
Cancer Society estimates that in 1996 there were approximately 52,900 new cases
of bladder cancer. Approximately 62 million Papanicolaou ("PAP") tests are
performed annually in the United States to screen for cervical cancer.

Studies indicate that early detection and the selection of appropriate
therapies can improve the survival rates of certain types of cancer. Vysis'
initial clinical cancer products are expected to improve patient survival rates
and quality of life by providing information that will enable selection of the
best possible therapy. Three of the Company's products for leukemia and other
myeloid disorders are currently FDA cleared for clinical use in the United
States. The Company's first breast cancer product, currently in late stage
clinical trials, is for the detection of HER-2/neu gene amplification, an
important predictive marker for the response to various therapeutic agents.

The Company's prenatal testing products provide information on genetic
abnormalities involved in mental retardation and other birth defects. The
Company estimates that in the United States and Western Europe more than 600,000
amniocentesis procedures were performed in 1996. Using traditional technology, 7
to 10 days are required to complete chromosomal testing from amniocentesis
specimens. In contrast, Vysis' clinical products provide accurate test results
within 24 hours. The French regulatory agency, Agence du Medicament, has
registered the Company's TriGen-TM- prenatal panel for the diagnosis of Down
syndrome and sex chromosome abnormalities. Marketing of this product was
initiated in France in June 1997. In the United States, the Company's
AneuVysion-TM- prenatal panel for the diagnosis of Down syndrome, sex chromosome
abnormalities and two additional chromosomal abnormalities, which together
account for 85% to 90% of chromosomal causes of mental retardation and other
birth defects, has been cleared by the FDA and its marketing was begun in
October 1997.

TECHNOLOGY PLATFORMS AND PRODUCTS

Genomic Disease Management testing requires the ability to assess
abnormalities of chromosomes, individual genes within chromosomes and specific
DNA sequences within genes. No single technology is capable of assessing all of
these different types of abnormalities. To address this issue, the Company has
developed three complementary technology platforms that detect the full range of
genetic abnormalities from large chromosomal aberrations to smaller
abnormalities associated with abnormal numbers of the same gene and the smallest
mutations within specific gene sequences. The Company believes these
complementary technologies will enable the clinician to provide a comprehensive
approach to genomic assessment in the management of disease.

4
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being able to simultaneously detect multiple genetic abnormalities in the same
specimen. Vysis expects to introduce a broad range of products based on each of
these platforms. This product development strategy is expected to reduce the
time to market and associated development costs for each product.

- FISH SYSTEM: This platform uses FISH technology, which provides the
ability to simultaneously assess multiple chromosomal and gene
abnormalities in a single intact cell. FISH also provides the ability to
perform cell by cell quantitative assessment of genetic changes in tissue
specimens routinely used by pathologists for diagnosis. The Company's FISH
System consists of instruments and image analysis workstations used with
the Company's patented direct label FISH probes. Vysis believes that its
direct label FISH probes are superior because the result produced is
easier to obtain and interpret. Three of the Company's FISH System
products for leukemia and other myeloid disorders are currently cleared
for clinical diagnostic use in the United States. Additionally, a FISH
based clinical diagnostic product for prenatal testing is registered and
marketed in France, and a similar product has been cleared by the FDA for
marketing in the United States. Clinical trials are underway for a breast
cancer product (HER-2/neu), which is intended to allow physicians to
choose the most effective and appropriate patient therapy.

- GCGH ARRAY SYSTEM: This platform uses the Company's patented comparative
genomic hybridization technology to survey the entire genome for
chromosomal changes in a single test, when a suspected genetic aberration
is unknown. Vysis is developing a ready-to-use array of DNA probes on a
miniaturized chip ("gCGH Array"). A camera based array reader and
customized software will be used to analyze each target on the array. This
system is intended to enable simultaneous assessment of a large number of
genes in a patient's specimen for abnormalities in the specific gene
count. The Company is currently developing products that are intended to
detect in a single specimen substantially all genes known to be amplified
in certain cancers. The Company is also developing a prenatal product that
is intended to simultaneously detect in a single test essentially all
chromosomal abnormalities known to be associated with common mental
retardation and other birth defects.

- MOLECULAR LAWN SYSTEM: This platform uses the Company's patented Q-beta
replicase ("QBR") amplification technology to detect specific gene
sequences. QBR provides a quantitative measure of a specific gene sequence
in either human, viral or bacterial DNA. Because the Molecular Lawn is a
self contained system and is being specifically designed for clinical use,
this QBR based system is intended to provide a more accurate, simple and
cost-effective alternative to other amplification technologies such as
polymerase chain reaction. This technology platform enables the detection
of small genetic targets associated with disease predisposition and early
detection of disease. The system includes a disposable test device and an
automated reader that will provide both qualitative and quantitative
results. The Company's initial product will be designed for the detection
of Human Papilloma Virus, which causes cervical cancer.

An integral part of the Company's technology platforms is its Image Analysis
Software, which is comprised of proprietary algorithms that enable the automated
display and analysis of FISH, gCGH Array and Molecular Lawn tests. The Company
believes that this technology will be essential to the development of its future
automated diagnostic systems.

5
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COMPANY STRATEGY

The Company's goal is to strengthen its position as a leading Genomic
Disease Management company providing products for the clinical assessment and
management of cancer, prenatal disorders and other genetic diseases. The key
elements of the Company's strategy are to:

- Focus on clinical disease management by developing rapid, accurate,
reliable, cost-effective and easy-to-use products that assess the genome
at all levels.

- Leverage the existing FISH System to develop products providing the
highest near-term medical value and significant revenue potential while
continuing to develop the next generation of Genomic Disease Management
products utilizing the gCGH Array and Molecular Lawn platforms.

- Capitalize on the Company's existing international sales and marketing
infrastructure to expand access to market opportunities worldwide.

- Obtain additional product leads through collaborations with leading
medical research institutions, incorporation of research results from the
Human Genome Project and continued expansion of the research product line
to help establish new clinical correlations.

- Continue to expand and strengthen the Company's intellectual property
position.

THE OFFERING

<TABLE>
<S> <C>
Common Stock offered by the Company.......... 3,500,000 shares
Common Stock to be outstanding after the
offering (1)................................ 9,501,260 shares
Use of Proceeds.............................. To accelerate product development, expand
sales and marketing capability, acquire
complementary technologies and intellectual
property rights as opportunities arise and
repay indebtedness. See "Use of Proceeds."
Nasdaq Stock Market symbol................... VYSI
</TABLE>

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(1) Includes 4,525,547 shares issuable upon the conversion of the Company's
outstanding Series A Preferred Stock and 403,741 shares issuable upon the
conversion of the Company's outstanding Series B Preferred Stock, all of
which preferred stock is owned by Amoco Technology Company ("ATC"). See
"Description of Capital Stock." Excludes, as of December 31, 1997, 953,468
shares issuable upon exercise of outstanding stock options under the
Company's Stock Incentive Plan. See "Management-- Stock Incentive Plan."

6
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SUMMARY FINANCIAL INFORMATION
(IN THOUSANDS, EXCEPT PER SHARE DATA)

<TABLE>
<CAPTION>
NINE MONTHS ENDED
YEAR ENDED DECEMBER 31, SEPTEMBER 30,
---------------------------------- ----------------------
1994 1995 1996 1996 1997
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<S> <C> <C> <C> <C> <C>
STATEMENT OF OPERATIONS DATA:
Revenues:
Product sales....................................... $ 5,373 $ 6,296 $ 11,022 $ 7,324 $ 10,558
Grant and other revenue............................. 30 921 2,216 1,647 1,667
---------- ---------- ---------- ---------- ----------
Total revenue..................................... 5,403 7,217 13,238 8,971 12,225
Cost of goods sold.................................... 3,486 4,022 5,529 3,742 4,773
---------- ---------- ---------- ---------- ----------
Gross profit.......................................... 1,917 3,195 7,709 5,229 7,452
---------- ---------- ---------- ---------- ----------
Operating expenses:
Research and development............................ 11,639 8,871 9,456 6,536 7,762
Selling, general and administrative................. 8,937 12,025 16,286 12,500 10,785
---------- ---------- ---------- ---------- ----------
Total operating expense........................... 20,576 20,896 25,742 19,036 18,547
---------- ---------- ---------- ---------- ----------
Loss from operations.................................. (18,659) (17,701) (18,033) (13,807) (11,095)
---------- ---------- ---------- ---------- ----------
Interest income--Amoco................................ -- -- 107 107 --
Interest expense--Amoco............................... -- -- (255) (88) (367)
---------- ---------- ---------- ---------- ----------
Net loss.............................................. $ (18,659) $ (17,701) $ (18,181) $ (13,788) $ (11,462)
---------- ---------- ---------- ---------- ----------
---------- ---------- ---------- ---------- ----------
Pro forma net loss per share(1)....................... $ (2.98) $ (2.26) $ (1.88)
---------- ---------- ----------
---------- ---------- ----------
Shares used in computing pro forma net loss per
share(1)............................................ 6,107 6,107 6,107
</TABLE>

<TABLE>
<CAPTION>
SEPTEMBER 30, 1997
-----------------------
AS
ACTUAL ADJUSTED(2)
---------- -----------
<S> <C> <C>
BALANCE SHEET DATA:
Cash and cash equivalents................................................................ $ 294 $ 37,283
Working capital (deficit)................................................................ (7,762) 36,608
Total assets............................................................................. 15,093 52,082
Notes payable--Amoco..................................................................... 7,381 --
Accumulated deficit...................................................................... (26,457) (26,457)
Total stockholders' equity............................................................... 56 44,426
</TABLE>

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(1) See Note 1 to the Consolidated Financial Statements for information
concerning the number of shares used in computing pro forma net
loss per share.

(2) As adjusted to give effect to the sale of 3,500,000 shares of Common Stock
offered by the Company at an assumed initial public offering price of $14.00
per share and the application of the net proceeds therefrom. See "Use of
Proceeds," "Capitalization" and "Description of Capital Stock."

7
<PAGE>
RISK FACTORS

IN ADDITION TO THE OTHER INFORMATION IN THIS PROSPECTUS, PROSPECTIVE
INVESTORS SHOULD CONSIDER CAREFULLY THE FOLLOWING RISK FACTORS:

UNCERTAIN CLINICAL MARKET ACCEPTANCE OF COMPANY PRODUCTS

Most of the Company's genetic testing products are currently being
distributed for research use only ("RUO"). If the Company's clinical diagnostic
products receive regulatory approval, Vysis will seek to introduce them into the
larger clinical diagnostic market. Acceptance of such products by geneticists,
clinicians, pathologists, oncologists, physicians and their patients for use in
clinical markets and the rate of such acceptance, if any, is uncertain and will
depend upon, among other things, the Company's ability to (i) increase the level
of awareness of its FISH, CGH, QBR and other technologies among the clinical
laboratories and physicians who are expected to order such tests, (ii) educate
the medical community regarding the benefits of managing disease with genomic
testing products, (iii) provide data demonstrating clinical correlations to
disease outcomes of the gene targets or genetic abnormalities detected by the
Company's products and (iv) obtain third party payers' approval of the Company's
products. There can be no assurance that the clinical market will accept the
Company's products to the extent necessary to make them commercially viable.
Failure of the Company to gain acceptance of its diagnostic products in the
clinical market or any significant delay in such acceptance may have a material
adverse effect on the Company's business, financial condition and results of
operations.

GOVERNMENT REGULATION; NO ASSURANCE OF REGULATORY APPROVAL

The preclinical and clinical testing, manufacturing, labeling, distribution
and promotion of the Company's products are subject to extensive and rigorous
government regulation in the United States and other countries. Noncompliance
with applicable requirements can result in enforcement action by the Food and
Drug Administration ("FDA") or comparable foreign regulatory bodies including,
among other things, warning letters, fines, injunctions, civil penalties, recall
or seizure of products, refusal to grant premarket clearances or approvals,
withdrawal of marketing clearances or approvals and criminal prosecution. Any
such enforcement action could have a material adverse effect on the Company's
business, financial condition and results of operations.

The Company generally is prohibited from marketing its diagnostic products
in the United States unless it obtains either 510(k) clearance or premarket
application ("PMA") approval from the FDA. The Company believes that it usually
takes from four to 12 months from submission to obtain 510(k) clearance, but it
can take longer. The process of obtaining PMA approval is much more costly,
lengthy and uncertain. In any event, there can be no assurance that 510(k)
clearance or PMA approval will be obtained in a timely fashion or at all. Such
clearance or approval may also have limitations on how the device may be
marketed that will limit its sales potential.

Distribution of the Company's products outside the United States is also
subject to regulation, which varies widely from country to country. The time
required to obtain needed regulatory clearance by particular foreign governments
may be longer or shorter than that required for FDA clearance or approval. In
addition, the export by the Company of certain of its products that have not yet
been cleared for domestic distribution may be subject to FDA export
restrictions. There can be no assurance that the Company will receive on a
timely basis, if at all, any foreign government or United States export
approvals necessary for the marketing of its products.

The Company's AKS-C- II Karyotype Imaging System (now named Quips-TM-)
received 510(k) clearance in 1990. The Company has made modifications to this
device that the Company believes do not require the submission of new 510(k)
notices. There can be no assurance, however, that the FDA would agree with any
of the Company's determinations not to submit a new 510(k) notice for any of
these changes or would not require the Company to submit a new 510(k) notice for
any of the changes made to the device. If the FDA

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requires the Company to submit a new 510(k) notice for any device modification,
the Company may be prohibited from marketing the modified device until the
510(k) notice is cleared by the FDA.

The Company believes that its FISH, gCGH Array and Molecular Lawn tests will
be placed in the "high complexity" category under the Clinical Laboratory
Improvement Amendments of 1988 ("CLIA") regulations, which will likely limit
their use to larger hospitals and clinical reference laboratories. There can be
no assurance that the CLIA regulations or future administrative interpretations
of CLIA will not have a material adverse impact on the Company by limiting the
potential market for the Company's FISH tests and other products.

Any devices manufactured or distributed by the Company pursuant to FDA
clearances or approvals will be subject to pervasive and continuing regulation
by the FDA and certain state agencies. The Company will be subject to routine
inspection by the FDA and will have to comply with the host of regulatory
requirements that usually apply to medical devices marketed in the United
States, including labeling regulations, the Quality System Regulation ("QSR"),
the Medical Device Reporting regulation (which requires a manufacturer to report
to the FDA certain types of adverse events involving its products), and the
FDA's prohibitions against promoting products for unapproved or "off-label"
uses. Unanticipated changes in existing regulatory requirements or adoption of
new requirements could have a material adverse effect on the Company's business,
financial condition and results of operations. The Company's failure to comply
with applicable regulatory requirements could result in enforcement action by
the FDA or foreign governments, which could have a material adverse effect on
the Company's business, financial condition and results of operations. See
"Business--Government Regulation."

HISTORY OF LOSSES; UNCERTAINTY OF FUTURE PROFITABILITY

The Company has incurred operating losses in each year since its inception.
The Company's losses have resulted principally from costs incurred in research
and development and from selling, general and administrative costs associated
with the Company's operations. These costs have exceeded the Company's revenues
which, to date, have principally been due to genetic testing product sales to
the clinical research market, food testing product sales, funding from
government research grants and payments from collaborators. The Company may
incur additional operating losses as a result of increases in its expenses for
research and product development, litigation, clinical trials/regulatory
approvals and expansion of sales and marketing capability.

The amount of future operating losses and time required by the Company to
reach profitability, if ever, are highly uncertain. The Company's ability to
generate significant revenues and become profitable is dependent in large part
on the ability of the Company to successfully commercialize products for
delivery to the clinical market. Delays in receipt of any necessary regulatory
approvals by the Company, or receipt of approvals by competitors, could
adversely affect the successful commercialization of the Company's products.
There can be no assurance that the Company will successfully commercialize any
of the clinical products that it is currently developing.

INTENSE COMPETITION

Competition in clinical diagnostics and genomics is intense and is expected
to increase as the market for Genomic Disease Management products develops.
Competition is and will continue to be based on quality, reliability, accuracy,
ease of use, price and product line offering. Oncor, Inc. ("Oncor") is a major
competitor in the supply of FISH products to the clinical research market and is
seeking to enter the clinical market with FISH products. Applied Imaging Corp.
and Perceptive Scientific Instruments, Inc. compete with Vysis in the marketing
of genetic imaging workstations. The Company is aware of other entities that
currently market RUO nucleic acid products, which may have the ability to
compete with the Company in the clinical market. In addition, many reference
laboratories and research institutions produce their own FISH probes for
internal use.

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Other companies are developing genomic assessment products, including "DNA
Chip" products for assessment of gene expression or gene sequence with potential
use for clinical diagnostics. Other diagnostic companies may enter the genetic
disease diagnostic market with nucleic acid based technologies. Many of the
Company's existing and potential competitors have substantially greater
financial, marketing, sales, distribution and technological resources than the
Company or may have substantial advantages over the Company in terms of research
and development expertise, experience in conducting clinical trials, experience
in regulatory matters, manufacturing efficiency, name recognition, ability to
obtain necessary intellectual property licenses, sales and marketing expertise
and distribution channels. There can be no assurance that the Company will be
able to compete successfully against current or future competitors. See
"Business--Competition."

DEPENDENCE UPON THE GENE DISCOVERY AND DISEASE CORRELATION EFFORTS OF OTHERS;
NEED TO OBTAIN DIAGNOSTIC APPLICATIONS OF DISCOVERIES

The Company's future prospects are dependent upon the rate at which
particular genes or genetic abnormalities are discovered and are correlated with
disease and upon the Company's ability to obtain the necessary rights to develop
and sell genetic tests based on these discoveries. There are a number of other
companies, institutions and government-financed entities engaged in the
discovery of the structure and function of the human genome, many of which have
greater financial, technical and human resources than the Company and its
collaborators. In addition, there are a finite number of genes in the human
genome, and companies and institutions performing gene discovery may seek to
identify, sequence and determine in the shortest time possible the biological
function of a large number of genes in order to obtain proprietary positions.
The Company's ability to obtain such rights also depends in part upon its
research collaborations and its ability to maintain and expand such
collaborations. No assurance can be given that the Company will be able to
obtain, on commercially reasonable terms, the rights to genes or correlations of
genetic abnormalities to disease necessary for marketing the Company's clinical
products. Failure to obtain such rights may have a material adverse effect on
the Company's business, financial condition and results of operations. See
"Business--Collaborations" and "Business--Ability to Practice Technology."

UNCERTAINTIES RELATING TO TECHNOLOGICAL APPROACHES

There can be no assurance that the Company will be able to overcome
technical challenges that may arise in connection with the development of its
clinical diagnostic products or, if resolved, the ultimate products will be
suitable for successful clinical commercialization. The development of such
products will require additional investment by the Company of its financial,
technical and other resources. Products incorporating the Company's technology
will also need to compete against well-established techniques and enhancements
to such techniques for analyzing genes and for diagnostics. There can be no
assurance that the Company's technology will compete successfully against
existing or future diagnostic techniques and products. In addition, the
development and commercialization of the Company's planned clinical products
will be subject to the risks of failure inherent in the development and
commercialization of any new technology. These risks include the possibilities
that any products based on these technologies will be found to be ineffective or
otherwise fail to receive the necessary regulatory clearances; that proprietary
rights of third parties will preclude the Company from marketing the products;
or that government and private third party payers will increasingly attempt to
contain health care costs by limiting both the extent of coverage and the
reimbursement rate for new diagnostic products and services.

The Company's development of its genetic imaging software products is
subject to all of the risks of the software development industry. There can be
no assurance that the Company's software development will not be adversely
impacted or delayed due to changes in its suppliers' products or software,
unforeseen programming needs, delay or failure to receive software development
services from third parties, or the Company's inability to obtain necessary
computer products, software and components on a timely basis. Any inability of
the Company to develop its genetic imaging software products on a timely basis
may have a material adverse effect on the Company.

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DEPENDENCE UPON COLLABORATIVE PARTNERS

The Company relies on its relationships with collaborators at academic and
other institutions that conduct research in areas of interest to the Company.
These collaborators are not employees of the Company. As a result, the Company
has limited control over their activities and, except as otherwise required by
its collaboration agreements, can expect only limited amounts of their time to
be dedicated to the Company's activities. The Company's collaborations with
third parties are an important element of the Company's strategy to obtain
rights to gene discoveries. There can be no assurance that the Company will be
able to negotiate additional collaboration arrangements with others or that its
existing or future collaborations will be successful. See
"Business--Collaborations" and "Business--Ability to Practice Technology."

UNCERTAIN ABILITY TO PRACTICE TECHNOLOGY

Consequently, the Company believes that its management of the business risks
presented by the intense patent competition in these fields is critical to its
ability to operate its business and to develop, manufacture, market and sell its
products. There can be no assurance that the Company will be able to
successfully manage these patent business risks to avoid infringing the
proprietary rights of others nor can there be any assurance that patent
infringement suits will not be brought against the Company. Any failure in its
management of these patent business risks may have a material adverse impact on
the Company's business, financial condition and results of operations.

The Company's success will also depend to a substantial degree upon its
ability to obtain and maintain patent protection, both in the United States and
in foreign countries, for its diagnostic products and methods and other
inventions that the Company believes patentable, as well as upon the Company's
ability to preserve its trade secrets and to protect its copyrights in software.
The Company's success will also depend to a substantial degree upon its
collaborators' and future licensors' ability to obtain and maintain patent
protection, both in the United States and in foreign countries, on gene
discoveries, the correlations of disease to genomic abnormalities and other
inventions relevant to the Company's business, as well as upon the Company's
collaborators' and future licensors' ability to preserve trade secrets and to
protect copyrights in software.

The patent position of a company utilizing biotechnology generally is highly
uncertain and involves complex legal and factual questions. There can be no
assurance that any patents owned by or licensed to the Company will not be
challenged and subsequently invalidated or circumvented, or that such patents
will be sufficiently broad to afford protection against third parties who
develop or use similar technology, or that any of such patents will be
successfully asserted against any infringing activity, or that any of the
Company's patent rights will be successfully cross-licensed to third parties in
exchange for a license under their patent rights. In addition, there can be no
assurance that any pending U.S. or foreign patent applications owned or licensed
by the Company or those acquired or licensed by the Company in the future will
result in issued patents, or that such applications will not be subject to
foreign opposition seeking the revocation of a Company patent or to United
States patent interference seeking a determination that the Company or its
collaborators were not the first inventor of a particular patent or patent
application, or that the Company or its collaborators will develop additional
technologies that are patentable, or that any patents owned or licensed to the
Company will provide a basis for commercially viable products or services.

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The Company is also aware of issued United States and foreign patents and
pending patent applications owned or controlled by third parties, which are
related to the Company's current or anticipated technologies. Specifically, the
Company is aware of issued United States and foreign patents and pending patent
applications owned or controlled by third parties, which are related to
significant elements of the Company's FISH, CGH and direct labeling
technologies, or to significant elements of the Company's anticipated use of its
QBR technologies, or to reagents useful in the performance of CGH or gCGH
assays. Although the Company believes that certain of these issued patents are
not infringed by the Company's current and planned operations, there can be no
assurance that the Company would be able to successfully assert such a position
in the courts, nor that such a position could be asserted without the Company's
incurring substantial or prohibitive costs. Furthermore, because United States
patent applications are maintained under conditions of confidentiality while the
applications are pending in the United States Patent and Trademark Office, there
may be pending patent applications filed by third parties of which the Company
is unaware and which relate to the Company's current or planned technologies. In
addition, third parties may in the future file patent applications having claims
that relate to the Company's services, processes or products. Persons holding or
licensing patent rights could bring legal actions against the Company claiming
that any of the Company's marketing, services, processes or products, of the
Company's collaborators' or its suppliers' services or products or of the
Company's customers' use of the Company's services or products infringe one or
more of their patents, and seek damages or injunctive relief. Patent litigation
is costly, and there can be no assurance that the Company would prevail in any
patent litigation brought against it. Further, the Company could be subject to
significant liabilities to such persons, may be required to obtain licenses from
such persons, or may be required to cease certain activities, and any of these
could have a material adverse effect upon the Company's business, financial
condition or results of operations. In addition, there can be no assurance that
the Company will be able to obtain such licenses on commercially reasonable
terms, or at all.

The Company also relies upon copyrights, copyright licenses and trade
secrets to protect its software and upon trade secrets to protect certain of its
unpatented proprietary technology. There can be no assurance that the Company
will be able to adequately protect its rights in such software and such
unpatented proprietary technology or that others will not independently develop
substantially equivalent technology or information, or that others will not
otherwise gain access to the Company's software and unpatented proprietary
technology or disclose the Company's software and unpatented proprietary
technology to third parties in a non-confidential manner.

The Company operates its business under various license and license option
agreements with other parties which provide rights to use technologies
fundamental to the Company's business. In addition, the Company's use of
technology licensed to it or developed by it with United States government
grants is also subject to the United States government's ability to exercise
rights to use such technology under the applicable license or grant. The
Company's failure to maintain in force any or all of these agreements or the
exercise of such government rights may have a material adverse effect on the
Company's business, financial condition and results of operations. The Company's
collaborators are also subject to risks which could limit or prevent their
practice of technology necessary for the success of their collaborations with
the Company. See "Business--Ability to Practice Technology."

LITIGATION

The Regents of the University of California (the "Regents") and the Company,
as exclusive licensee, are plaintiffs in a patent infringement suit against
Oncor in the United States District Court in San Francisco, California. The suit
asserts that Oncor's marketing of various DNA probe products infringes the
Regents' U.S. Patent No. 5,447,841. Oncor's answer to the complaint asserts that
the patent is invalid based on prior art and the failure to disclose the best
mode of practicing the invention and that it is unenforceable due to inequitable
conduct that occurred during prosecution of the patent. In a pre-trial order
dated August 19, 1997, the court granted the Company summary judgment that the
patent's claims are valid over the prior art and that use of certain of Oncor's
probes infringe the claims. The trial of the

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remaining issues is scheduled to begin in April 1998. If Oncor were to succeed
in invalidating the patent or having it declared unenforceable, this may have a
material adverse effect on the Company's market position and future business
prospects.

The Company and Amoco are defendants in a suit pending in the United States
District Court in San Diego, California brought by Gen-Probe, Inc.
("Gen-Probe"). The suit alleges infringement of U.S. Patent Nos. 4,851,330 and
5,288,611 (the "Kohne Patents"). The Kohne Patents are alleged to apply
generally to the detection, identification and quantification of non-viral
organisms using DNA probes selected to target sequences of ribosomal RNA. The
allegedly infringing activities are the manufacture, use and sale of reagents
and kits for detecting certain food and environmental pathogens. The suit also
alleges various claims that the Company competed unfairly with Gen-Probe. This
suit has been stayed pending the outcome of a separate suit brought against
Gen-Probe by the Center for Neurologic Study ("CNS") challenging Gen-Probe's
claim to sole ownership of the Kohne Patents. CNS asserts that the invention of
the Kohne Patents were made by David Kohne while he was affiliated with CNS and
supported by a grant from the National Institutes of Health naming CNS as the
grantee institution. CNS seeks damages and title in the Kohne Patents. The
Company has contingent rights to acquire an exclusive license with the right to
grant sub-licenses under such rights as CNS may obtain in the Kohne Patents.
Further, the Company has contractually agreed with CNS to grant sub-licenses at
commercially fair and reasonable terms under the Kohne patents should it acquire
the exclusive license. On December 16, 1997, the jury in the CNS suit determined
that its claims were barred as untimely. The Company understands that CNS is
evaluating its available options. There can be no assurance that the Company
will obtain rights under such Kohne Patents.

There can be no assurance that Gen-Probe will not assert additional counts
of infringement based on any additional patents issued from the applications
underlying the Kohne Patents or will not assert additional causes of action
against the Company. Although the Company believes that it has meritorious
defenses to the suit by Gen-Probe against the Company, there can be no assurance
that the Company will ultimately prevail. An adverse determination could include
an award of treble damages and/or attorneys' fees, which could have a material
adverse effect on the financial condition and results of operations of the
Company. Furthermore, an adverse determination in such suit may limit future
business opportunities that the Company might otherwise be able to exploit in
the area of infectious disease detection.

Prior to the closing of this offering, the Company and Amoco, will enter
into a Cooperation Agreement that will provide that Amoco and the Company will
cooperate in the defense of the suit brought by Gen-Probe and will include an
agreement relating to the allocation of any resulting liability between the
Company and Amoco. See "Business--Litigation."

SOCIAL AND LEGAL IMPLICATIONS OF GENETIC TESTING

The use of genetic tests raises a number of social issues and concerns and
is the subject of considerable controversy. These controversies may lead to
efforts (including legislative efforts) to prohibit or otherwise limit the use
of such products. These efforts could result in a reduction in the size of the
potential market for the Company's products. The Company is unable to predict
how concerns regarding the social and legal implications of genetic testing will
affect the market for genetic testing products.

The prospect of broadly available genomic testing products which evaluate
genetic predisposition to disease has also raised issues regarding the
appropriate utilization and the confidentiality of information provided by such
testing. It is possible that insurers or employers could discriminate against
persons with a genetic predisposition for disease. Such discrimination could
cause governmental authorities, for social or other purposes, to limit the use
of genetic testing or prohibit testing for genetic predispositions to certain

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conditions. If efforts by the Company and others to mitigate potential
discrimination are not successful, the Company could experience a delay or
reduction in test acceptance, which could have a material adverse effect on the
Company's ability to commercialize its potential testing products for genetic
predisposition.

FUTURE CAPITAL REQUIREMENTS; UNCERTAINTY OF ADDITIONAL FUNDING

The Company has funded its operations to date primarily through capital
contributions and loans from Amoco. Amoco has advised the Company that it does
not intend to continue such funding following this offering. The Company's
future capital requirements will depend on many factors, including progress of
the Company's research and development programs, the results and cost of
clinical correlation testing of the Company's genetic products, the cost of
filing, prosecuting, enforcing and defending patent claims, the cost and timing
associated with obtaining regulatory approval for proposed clinical products,
competing technological and market developments, payments received or disbursed
under collaborative agreements, changes in collaborative research relationships,
payments under government research grants, the costs and license revenue
associated with potential commercialization of its gene discovery opportunities
and other administrative and legal expenses. Because of the Company's potential
long-term capital requirements, it may need to access the public or private
equity or debt markets from time to time. There can be no assurance that any
such additional funding will be available to the Company, or if available, that
it will be on reasonable terms. If adequate funds are not available, the Company
may be required to scale down research and development programs, curtail capital
expenditures, and reduce marketing and other operating expenses. There can be no
assurance that the Company will be successful in conducting its operations on an
independent basis. See "Certain Transactions."

BROAD DISCRETION IN ALLOCATION AND USE OF PROCEEDS

Although the Company intends to use the net proceeds of this offering to
accelerate product development, expand sales and marketing capability, acquire
complementary technologies and intellectual property rights as opportunities
arise and repay indebtedness owed to Amoco, the Company has not yet identified
the specific amounts to be allocated to any of the foregoing uses other than
repayment of indebtedness owed to Amoco (approximately $11.2 million as of
December 31, 1997). The Company's management will retain broad discretion as to
the allocation of the net proceeds of this offering. See "Use of Proceeds."

DEPENDENCE ON THIRD-PARTY REIMBURSEMENT

The future success of the Company's diagnostic products in the clinical
market will depend, in part, on the availability of adequate reimbursement from
third-party payers such as United States or foreign government entities, managed
care organizations and private insurance plans. Significant uncertainty exists
concerning third-party reimbursement for the use of medical tests incorporating
new technology. Reimbursement by a third-party payer generally depends on
factors such as the payer's determination that the product is clinically useful
and cost-effective, is not experimental or investigational, and is medically
necessary and appropriate for the specific patient. Since reimbursement approval
is required from each individual payer, seeking such approvals is a time
consuming and costly process which requires the Company to provide scientific
and clinical support for the use of its products for their approved indications
to each payer separately. There can be no assurance that third-party
reimbursement will be consistently available for the Company's products or that
such third-party reimbursement will be adequate. In addition, health care
reimbursement systems vary from country to country and, accordingly, there can
be no assurance that third-party reimbursement will be available for the
Company's products in any particular country in which the Company markets its
products.

LIMITED SALES AND MARKETING EXPERIENCE

To date the Company has sold almost all of its genetic testing products for
RUO purposes and has only limited experience in selling to the clinical market.
There can be no assurance that the Company will

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be able to establish a sales force sufficient to meet the demands of the
clinical market, educate the market as to the utility of the Company's products
or otherwise successfully distribute its products. Failure to do so would have a
material adverse effect on the Company's business, financial condition and
results of operations. See "Business--Sales and Marketing."

LIMITED MANUFACTURING EXPERIENCE

The Company has limited commercial scale manufacturing experience and
capabilities. The Company anticipates it will need to expand substantially its
manufacturing capabilities in order to commercialize effectively its clinical
products. There can be no assurance that the Company will be able to recruit and
retain skilled manufacturing personnel to establish sufficient manufacturing
capability and capacity or manufacture the Company's products in a timely
manner, at a cost or in quantities necessary to make them commercially viable,
in conformance with ISO 9001 requirements or the FDA's QSR, or in a manner that
otherwise ensures product quality. See "Business--Manufacturing."

UNCERTAINTIES RELATED TO GOVERNMENT FUNDING

A substantial portion of the Company's current genetic testing products are
sold to reference laboratories and academic institutions for research purposes.
Certain of these entities rely on United States or foreign government grants to
fund their research efforts. In addition, government funding supports many of
the gene discovery efforts and disease correlation studies currently conducted
by academic research institutions and others. A significant reduction in
government funding of these entities may have a material adverse effect on the
Company by reducing sales of the Company's RUO products or by slowing the rate
of gene discoveries or of correlations of abnormalities to disease on which new
diagnostic products will be based.

PRODUCT LIABILITY

The Company's business is subject to product liability risks inherent in the
design, development, testing, manufacturing and marketing of the Company's
products, including its clinical diagnostics and its food testing products, for
their particular applications. There can be no assurance that product liability
claims will not be asserted against the Company nor any assurance that product
liability claims or defense of such claims will not have a material adverse
effect on the Company's financial results. There is also a significant
difference in the applicable federal law governing preemption of state law based
product liability claims concerning medical devices that are certified by the
FDA under the 510(k) process, compared to those approved by the FDA under a PMA.
The United States Supreme Court recently held that there is no federal
preemption of such state law claims where the medical device is certified under
the 510(k) process. Thus a federal preemption defense may not be available in
product liability claims against medical devices approved via the 510(k)
process, whereas the defense may be available for PMA approved devices. The
Company currently maintains product liability insurance coverage of $1.0 million
per occurrence, and $10 million in the aggregate. There can be no assurance that
this coverage will be adequate to protect the Company against future product
liability claims or that product liability insurance will be available to the
Company in the future on commercially reasonable terms, if at all. Furthermore,
there can be no assurance that the Company will be able to avoid significant
adverse publicity resulting from any future product liability claims.

ENVIRONMENTAL REGULATION

The Company is subject to a variety of local, state and federal government
regulations relating to the storage, discharge, handling, emission, generation,
manufacture and disposal of toxic, infectious or other hazardous substances used
to manufacture the Company's products and in the Company's research. The failure
to comply with current or future regulations could result in the imposition of
substantial fines against the Company, suspension of production or research,
alteration of its manufacturing processes or cessation of operations. There can
be no assurance that the Company will not be required to incur significant costs
to comply with any such laws and regulations in the future, or that such laws or
regulations

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will not have a material adverse effect on the Company's business, financial
condition and results of operations. Any failure by the Company to control the
use, disposal, removal or storage of, or to adequately restrict the discharge
of, or assist in the cleanup of, hazardous chemicals or hazardous, infectious or
toxic substances could subject the Company to significant liabilities, including
joint and several liability under certain statutes. The imposition of such
liabilities may have a material adverse effect on the Company's business,
financial condition and results of operations.

DEPENDENCE ON SINGLE SOURCE SUPPLIERS

Certain key components of the Company's products are currently provided to
the Company by single sources. The Company does not have long-term supply
contracts with any of such suppliers, and the Company has not arranged
alternative supply sources. In the event that the Company is unable to obtain
sufficient quantities of such components on commercially reasonable terms, or in
a timely manner, the Company would not be able to manufacture its products on a
timely and cost-competitive basis.

DEPENDENCE ON KEY PERSONNEL

Because of the specialized scientific nature of the Company's business, the
Company is highly dependent upon its ability to attract and retain qualified
scientific and executive personnel. There can be no assurance that the Company
will be successful in attracting and retaining these skilled persons who
generally are in high demand by pharmaceutical and biotechnology companies and
by universities and other research institutions. The loss of, or the inability
to attract, key scientific and executive personnel may have a material adverse
effect on the Company. The Company does not have employment agreements with any
of its employees and does not maintain any "key-man" life insurance policies.
See "Business-- Employees."

INTERNATIONAL BUSINESS UNCERTAINTIES

Approximately 35% of the Company's revenues in 1996 was generated from
sources outside of the United States and significant future growth potential for
the Company's products is located outside of the United States. In the near
term, product revenue from sources outside the United States may increase as a
percentage of total product revenue due to the introduction of clinical
diagnostic products in the European market prior to their introduction in the
United States. As a result of this significant foreign source revenue, the
Company's business is subject to the risks of doing business abroad, including
exchange rate fluctuations, import and export regulations, possible restrictions
on the transfer of funds and greater difficulty in collecting accounts
receivable. In addition, products made available in the United States and
internationally may be subject to regulation by various foreign countries
pursuant to laws which may vary widely from those in the United States. The
Company may incur substantial expense in complying with such laws. Finally,
legal and non-legal entry barriers may prevent the Company from entering certain
foreign markets or limit its market penetration.

CONTINUED CONTROL BY PRINCIPAL STOCKHOLDER

Following completion of this offering, Amoco will beneficially own
approximately 63% of the Company's outstanding shares of Common Stock (or
approximately 60% if the Underwriters' over-allotment option is exercised in
full). As a result, Amoco will control the Company and will be able to elect all
of the Company's directors and to determine the outcome of corporate actions
requiring stockholder approval. Amoco also will be able to prevent a change of
control of the Company. The Company anticipates that immediately following this
offering three of the Company's seven directors will be employees of Amoco.

NO PRIOR MARKET FOR COMMON STOCK; POSSIBLE VOLATILITY OF STOCK PRICE

Prior to this offering, there has been no public market for the Common
Stock, and there can be no assurance that an active trading market for the
Common Stock will develop or be sustained. The initial

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public offering price will be determined through negotiations between the
Company and the representatives of the Underwriters and may not be indicative of
prices that will prevail in the trading market. See "Underwriting" for
information relating to the factors considered in determining the initial public
offering price. The stock market in recent years has experienced extreme price
and volume fluctuations that have particularly affected the market prices of
many biotechnology companies. These fluctuations, as well as factors such as
announcements of technological developments or new products by the Company or
its competitors, litigation involving the Company or its licensors, developments
concerning intellectual property rights, regulatory changes, or variations in
the Company's quarterly results of operations, as well as announcements relating
to the Company's industry generally, may materially and adversely affect the
market price of the Common Stock.

ANTI-TAKEOVER PROVISIONS

The Company's Certificate of Incorporation allows the Board of Directors,
without stockholder approval, to issue additional shares of Common Stock or
establish one or more series of preferred stock with such preferences and rights
as the Board of Directors may determine. This provision may have the effect of
making it more difficult for a third party to acquire, or of discouraging a
third party from attempting to acquire, control of the Company. In addition, the
Company is subject to Section 203 of the Delaware General Corporation law which
restricts the ability of certain stockholders of the Company to enter into a
merger or other business combination with the Company. The foregoing could limit
the price that certain investors might be willing to pay in the future for
shares of Common Stock. See "Description of Capital Stock."

FUTURE SALES OF COMMON STOCK

Upon completion of this offering, there will be 9,501,260 shares of Common
Stock outstanding. The 3,500,000 shares of Common Stock sold pursuant to this
offering (plus any shares sold pursuant to the Underwriters' over-allotment
option) will be tradeable without restrictions by persons other than
"affiliates" of the Company. Amoco may also sell shares into the market pursuant
to Rule 144 promulgated under the Securities Act of 1933, as amended (the
"Securities Act"). Pursuant to a registration rights agreement with the Company,
Amoco, the Company's principal stockholder, may demand that the Company register
its shares of Common Stock under the Securities Act at any time following 180
days after the date of this Prospectus. (However, Amoco has agreed with the
Underwriters that it will not sell any shares of Common Stock for a period of
one year following the date of this Prospectus without the consent of Furman
Selz LLC. See "Underwriting.") The Company intends to file, shortly after
completion of this offering, a registration statement covering all 985,402
shares of Common Stock reserved for issuance in connection with the Company's
Stock Incentive Plan. Sales of any of the foregoing shares into the public
market could adversely affect the then prevailing market price of the Common
Stock. See "Shares Eligible for Future Sale."
DILUTION

Based upon an assumed initial public offering price per share of $14.00 (and
assuming no exercise of the Underwriters' over-allotment option), the Company's
pro forma net tangible book value per share of Common Stock as of September 30,
1997, after giving effect to the transactions set forth in "Capitalization,"
would be $4.38. Accordingly, purchasers of Common Stock offered hereby would
suffer immediate and substantial dilution in book value per share of $9.62. See
"Dilution."

17
<PAGE>
THE COMPANY

The Company was incorporated in Delaware on April 18, 1991. The Company's
business represents the consolidation of multiple research units and programs of
Amoco. In 1994, Amoco began consolidation of all of its medical diagnostic
businesses and related research under the Company. In March 1994, Amoco
contributed to the Company all of its genetic disease related assets, including
the stock of Imagenetics Incorporated (an Illinois corporation). Also in March
1994, Amoco contributed all of its infectious disease related assets and the
stock of Gene-Trak, Inc. to the Company. Gene-Trak, Inc. had previously acquired
certain infectious disease related assets from Genzyme Corporation and Amoco,
including all of the interest in Gene-Trak Systems, a joint venture partnership
for infectious disease diagnostics established by Amoco and Integrated Genetics
in 1986. The Company's wholly owned subsidiary, Gene-Trak Systems Industrial
Diagnostics Corporation, manufactures and markets food testing kits based on DNA
probes.

The Company's executive offices are located at 3100 Woodcreek Drive, Downers
Grove, Illinois 60515 and its telephone number is (630) 271-7000.

USE OF PROCEEDS

The Company will receive approximately $44,370,000 from the sale of the
3,500,000 shares of Common Stock in this offering based on an assumed price to
the public of $14.00 per share (after deducting underwriting discounts and
commissions and estimated expenses payable by the Company). The Company intends
to use the net proceeds of this offering to: (i) accelerate product development,
including the gCGH Array and Molecular Lawn platforms and related automated
instrumentation, (ii) expand direct sales and marketing capability in the United
States and Europe in anticipation of further clinical product introductions,
(iii) acquire complementary technologies and intellectual property rights as
opportunities arise and (iv) repay outstanding principal and accrued interest
(approximately $11.2 million as of December 31, 1997) on a note held by Amoco,
which bears interest at 7.5% per annum, and which is due and payable upon
completion of this offering. Such indebtedness was used to finance the Company's
operating losses, which are primarily the result of the Company's continuing
research and development activities and the expansion of its sales and marketing
capability. The remainder of the net proceeds will be used for working capital
and general corporate purposes.

Other than repayment of indebtedness owed to Amoco, the Company has not
determined the portion of the net proceeds to be allocated to any of the uses
decribed above. Actual expenditures by the Company for any of these purposes may
vary significantly depending upon a number of factors, including progress of the
Company's product development programs, the cost and timing associated with
obtaining regulatory approvals for clinical products and whether or not
appropriate acquisition opportunities become available. Pending use of the net
proceeds as set forth above, they will be invested in short-term, investment
grade, interest bearing securities.

DIVIDEND POLICY

The Company currently intends to retain its earnings to finance future
growth and does not anticipate paying any cash dividends on its Common Stock in
the foreseeable future. Any determination as to the payment of dividends will
depend upon the future results of operations, capital requirements and financial
condition of the Company and its subsidiaries and such other facts as the Board
of Directors of the Company may consider, including any contractual or statutory
restrictions on the Company's ability to pay dividends.

18
<PAGE>
CAPITALIZATION

The following table sets forth, as of September 30, 1997, (i) the actual
capitalization of the Company, (ii) pro forma to give effect to the conversion
of all of the outstanding shares of Series A and Series B Convertible Preferred
Stock into 4,525,547 and 403,741 shares, respectively, of Common Stock upon
completion of this offering (the "Conversion") and (iii) pro forma as adjusted
to give effect to the Conversion and to give effect to the sale by the Company
of the 3,500,000 shares of Common Stock offered hereby at an assumed initial
public offering price of $14.00 per share, after deducting underwriting
discounts and commissions and estimated expenses of the offering payable by the
Company and the application of the net proceeds therefrom. See "Use of
Proceeds." This table should be read in conjunction with the Company's
Consolidated Financial Statements and the Notes thereto included elsewhere
herein.

<TABLE>
<CAPTION>
SEPTEMBER 30, 1997
------------------------------------
PRO FORMA
ACTUAL PRO FORMA AS ADJUSTED
---------- ----------- -----------
(IN THOUSANDS)
<S> <C> <C> <C>
Notes payable - Amoco(1)..................................................... $ 7,381 $ 7,381 $ --
---------- ----------- -----------
Stockholders' equity:
Series A convertible preferred stock, $0.001 par value; 6,200,000 shares
designated, issued and outstanding actual; none issued and outstanding
pro forma and pro forma as adjusted...................................... 6 -- --
Series B convertible preferred stock, $0.001 par value; 553,126 shares
designated, issued and outstanding actual; none issued and outstanding
pro forma and pro forma as adjusted...................................... 1 -- --
Common stock, $0.001 par value; 35,000,000 shares authorized; 1,071,972
shares issued and outstanding actual; 6,001,260 shares issued and
outstanding pro forma and 9,501,260 shares issued and outstanding pro
forma as adjusted(2)..................................................... 1 6 10
Additional paid-in capital................................................. 27,012 27,014 71,380
Deferred compensation...................................................... (259) (259) (259)
Cumulative translation adjustment.......................................... (248) (248) (248)
Accumulated deficit........................................................ (26,457) (26,457) (26,457)
---------- ----------- -----------
Total stockholders' equity............................................... 56 56 44,426
---------- ----------- -----------
Total capitalization..................................................... $ 7,437 $ 7,437 $ 44,426
---------- ----------- -----------
---------- ----------- -----------
</TABLE>

- ------------------------

(1) The balance of the note payable to Amoco as of December 31, 1997 was
approximately $11.2 million. See "Use of Proceeds."

(2) Excludes as of December 31, 1997 (i) 953,468 shares of Common Stock issuable
upon exercise of outstanding options and (ii) 18,356 shares of Common Stock
available for future option grants or stock issuances under the Company's
Stock Incentive Plan. See "Management--Stock Incentive Plan," and Note 8 of
Notes to Consolidated Financial Statements.

19
<PAGE>
DILUTION

The pro forma net tangible book value of the Company at September 30, 1997
was approximately $(2,708,000), or $(0.45) per share. "Pro forma net tangible
book value" per share is determined by dividing net tangible book value of the
Company (total tangible assets less total liabilities) by the number of shares
of Common Stock outstanding (after giving effect to the conversion of all
outstanding shares of Series A and Series B Preferred Stock of the Company).
Without taking into account any other changes in the net tangible book value at
September 30, 1997, other than to give effect to the receipt by the Company of
the net proceeds from the sale of 3,500,000 shares of Common Stock by the
Company offered hereby at an assumed initial public offering price of $14.00 per
share, and after deducting estimated underwriting discounts and commissions and
offering expenses, the Company's pro forma net tangible book value as of
September 30, 1997 would have been $41,662,000, or $4.38 per share. This
represents an immediate increase in pro forma net tangible book value of $4.83
per share to existing stockholders and an immediate dilution of $9.57 per share
to new investors purchasing Common Stock in this offering. The following table
illustrates this dilution:

<TABLE>
<CAPTION>
<S> <C> <C>
Assumed initial public offering price.................................................... $ 14.00
Pro forma net tangible book value per share at September 30, 1997........................ $ (0.45)
Increase per share attributable to new investors in this offering........................ 4.83
---------
Pro forma net tangible book value per share after offering............................... 4.38
---------
Dilution per share to new investors...................................................... $ 9.62
---------
---------
</TABLE>

The following table summarizes, on a pro forma basis at September 30, 1997,
the difference between existing stockholders and new investors with respect to
the number of shares of Common Stock purchased from the Company, the total
consideration paid to the Company and the average consideration paid per share:

<TABLE>
<CAPTION>
SHARES PURCHASED TOTAL CONSIDERATION AVERAGE
------------------------ ------------------------ PRICE PER
NUMBER PERCENT AMOUNT PERCENT SHARE
------------- --------- ------------- --------- --------------
<S> <C> <C> <C> <C> <C>
Existing stockholders (1).................... 6,001,260 63.2% $ 26,530,000 35.1% $ 4.42
New investors in this offering (2)........... 3,500,000 36.8 49,000,000 64.9 14.00
------------- --------- ------------- ---------
9,501,260 100.0% $ 75,530,000 100.0% 7.95
------------- --------- ------------- ---------
------------- --------- ------------- ---------
</TABLE>

- ------------------------

(1) Includes 4,525,547 and 403,741 shares issuable upon the conversion of the
Company's outstanding Series A and Series B Preferred Stock, respectively,
all of which preferred stock is owned by Amoco. See "Description of Capital
Stock."

(2) If the Underwriters' over-allotment option is exercised in full, the shares
purchased from the Company will increase to 4,025,000 (40.1% of the shares
outstanding after this offering) and the total consideration paid to the
Company by new investors will increase to $56,350,000 (68.0% of the
consideration paid to the Company by all shareholders).

The foregoing tables assume no exercise of options to purchase an aggregate
of 957,969 shares of Common Stock outstanding at September 30, 1997. To the
extent outstanding options are exercised, there will be further dilution to new
investors. See Note 8 of Notes to Consolidated Financial Statements.

20
<PAGE>
SELECTED FINANCIAL INFORMATION

The statement of operations data presented below for the years ended
December 31, 1994, 1995 and 1996 and for the nine months ended September 30,
1997, and the balance sheet data at December 31, 1995 and 1996 and September 30,
1997 have been derived from the financial statements of the Company, which have
been audited by Price Waterhouse LLP, independent accountants. The statement of
operations data for the years ended December 31, 1992 and 1993, the balance
sheet data at December 31, 1992, 1993 and 1994, the statement of operations data
for the nine months ended September 30, 1996 are unaudited but have been
prepared on the same basis as the audited consolidated financial statements and
in the opinion of management include all adjustments, consisting of normal
recurring adjustments, necessary for the fair presentation thereof. The data for
the nine months ended September 30, 1997 are not necessarily indicative of the
results for an entire year. The data presented below should be read in
conjunction with the Company's Consolidated Financial Statements and Notes
thereto included elsewhere in this Prospectus.

<TABLE>
<CAPTION>
NINE MONTHS ENDED
YEAR ENDED DECEMBER 31, SEPTEMBER 30,
----------------------------------------------------- --------------------
1992 1993 1994 1995 1996 1996 1997
--------- --------- --------- --------- --------- --------- ---------
(IN THOUSANDS, EXCEPT PER SHARE DATA)
<S> <C> <C> <C> <C> <C> <C> <C>
STATEMENT OF OPERATIONS DATA:
Revenues:
Product sales..................... $ 4,541 $ 3,513 $ 5,373 $ 6,296 $ 11,022 $ 7,324 $ 10,558
Grant and other revenue........... -- 67 30 921 2,216 1,647 1,667
--------- --------- --------- --------- --------- --------- ---------
Total revenue................... 4,541 3,580 5,403 7,217 13,238 8,971 12,225
Cost of goods sold.................. 2,383 2,831 3,486 4,022 5,529 3,742 4,773
--------- --------- --------- --------- --------- --------- ---------
Gross profit........................ 2,158 749 1,917 3,195 7,709 5,229 7,452
--------- --------- --------- --------- --------- --------- ---------
Operating expenses:
Research and development.......... 11,601 10,550 11,639 8,871 9,456 6,536 7,762
Selling, general and
administrative.................. 2,920 4,541 8,937 12,025 16,286 12,500 10,785
--------- --------- --------- --------- --------- --------- ---------
Total operating expenses........ 14,521 15,091 20,576 20,896 25,742 19,036 18,547
--------- --------- --------- --------- --------- --------- ---------
Loss from operations................ (12,363) (14,342) (18,659) (17,701) (18,033) (13,807) (11,095)
--------- --------- --------- --------- --------- --------- ---------
Interest income--Amoco.............. -- -- -- -- 107 107 --
Interest expense--Amoco............. -- -- -- -- (255) (88) (367)
--------- --------- --------- --------- --------- --------- ---------
Net loss............................ $ (12,363) $ (14,342) $ (18,659) $ (17,701) $ (18,181) $ (13,788) $ (11,462)
--------- --------- --------- --------- --------- --------- ---------
--------- --------- --------- --------- --------- --------- ---------
Pro forma net loss per
share(1)(2)....................... $ (2.98) $ (2.26) $ (1.88)
--------- --------- ---------
--------- --------- ---------
Shares used in computing pro forma
net loss per share(1)(2).......... 6,107 6,107 6,107
</TABLE>

21
<PAGE>

<TABLE>
<CAPTION>
DECEMBER 31, SEPTEMBER 30,
--------------------------------------------------------- -------------
1992 1993 1994 1995 1996 1997
--------- ---------- ---------- ---------- ---------- -------------
(IN THOUSANDS)
<S> <C> <C> <C> <C> <C> <C>
BALANCE SHEET DATA:
Cash.................................... $ -- $ -- $ 10 $ 247 $ 48 $ 294
Working capital (deficit)............... 1,179 1,045 758 (2,625) (6,622) (7,762)
Total assets............................ 5,414 12,718 17,574 19,167 15,115 15,093
Notes payable--Amoco.................... -- -- -- -- 5,106 7,381
Accumulated deficit..................... -- -- -- -- (14,995) (26,457)
Total stockholders' equity.............. 4,340 11,720 15,510 13,185 2,493 56
</TABLE>

- ------------------------

(1) See Note 1 to Consolidated Financial Statements for information concerning
the number of shares used in computing pro forma net loss per share.

(2) Pro forma supplementary net loss per share for the nine months ended
September 30, 1997 amounts to $(1.66) based upon an assumed 6,690,000
weighted average common shares outstanding and a net loss of $(11,095,000).
Pro forma supplementary net loss per share is calculated as if the Company
sold on January 1, 1997, 582,557 shares of Common Stock, representing the
number of shares of Common Stock required to be sold at the initial public
offering price of $14.00 per share, net of underwriting discounts
commissions and estimated expenses, in order for the Company to repay the
note payable to Amoco.

22
<PAGE>
MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
CONDITION AND RESULTS OF OPERATIONS

OVERVIEW

Vysis is a leading Genomic Disease Management company that develops,
commercializes and markets clinical products that provide information critical
to the evaluation and management of cancer, prenatal disorders and other genetic
diseases. Vysis currently markets five FDA cleared clinical products in addition
to distributing over 240 research products through its direct sales operations
in the United States and Europe and a worldwide distribution network covering 28
countries. It also markets proprietary genetic imaging workstations for clinical
and research use, with an installed base of over 320 proprietary genetic
workstations at 224 laboratories in 18 countries. The Company also develops,
manufactures and commercializes products used by food processors and quality
control laboratories for the detection and identification of food-borne
pathogens. See Note 9 of Notes to Consolidated Financial Statements for
financial information of the Company by geographic area.

RESULTS OF OPERATIONS

NINE MONTHS ENDED SEPTEMBER 30, 1997 AND SEPTEMBER 30, 1996

Total revenue increased to $12.2 million for the nine months ended September
30, 1997 from $9.0 million for the nine months ended September 30, 1996, an
increase of $3.2 million or 36%. Product sales accounted for the increase,
primarily as a result of increased product shipments in the United States and
the incorporation of nine full months of operations in France and the United
Kingdom. Grant and other revenue in 1997 of $1.7 million included $1.1 million
earned under two United States Department of Commerce research grants awarded to
Vysis in 1995. Both grants are administered through the Advanced Technology
Program of the National Institute of Standards and Technology. Grant and other
revenue in 1997 also included revenue of $450,000 from Fujisawa Pharmaceutical
Co., Ltd. ("Fujisawa") pursuant to a distribution agreement signed in July 1995.
Grant and other revenue for the nine months ended September 30, 1996 of $1.6
million consisted primarily of $1.4 million earned under the Company's two above
mentioned research grants and the Fujisawa agreement.

Cost of goods sold increased to $4.8 million for the nine months ended
September 30, 1997 from $3.7 million for the nine months ended September 30,
1996. The increase in cost of goods sold resulted from an increase in the volume
of product sold. As a percentage of total revenue, gross profit increased from
58.3% for the nine months ended September 30, 1996 to 61.0% for the nine months
ended September 30, 1997, primarily as a result of a change in product sales mix
toward higher margin products.

Research and development expense increased to $7.8 million for the nine
months ended Septem-
ber 30, 1997 from $6.5 million for the nine months ended September 30, 1996. The
$1.3 million increase reflects the hiring of additional scientists to support
the development of the Company's three technology platforms and expense of
$900,000 for the nine months ended September 30, 1997 relating to an agreement
with a collaborative partner.

Selling, general and administrative expense decreased to $10.8 million for
the nine months ended September 30, 1997 from $12.5 million for the nine months
ended September 30, 1996. This decrease was due to reduced general and
administrative expenses of $2.8 million primarily attributable to lower
litigation costs, partially offset by a $1.1 million increase in selling expense
primarily due to the hiring of additional sales and marketing personnel and
other expenses incurred in line with the overall expansion of operations.

The Company sold two buildings in Framingham, Massachusetts in January 1996
for $6.7 million in cash. The Company earned interest income from Amoco of
$107,000 during the nine months ended September 30, 1996 as a result of Amoco's
investment of the Company's real estate sale proceeds. The

23
<PAGE>
Company incurred interest expense of $367,000 during the nine months ended
September 30, 1997 and $88,000 during the nine months ended September 30, 1996
related to the note payable to Amoco.

TWELVE MONTHS ENDED DECEMBER 31, 1996 AND DECEMBER 31, 1995

Total revenue increased to $13.2 million for the twelve months ended
December 31, 1996 from $7.2 million for the twelve months ended December 31,
1995, an increase of $6.0 million or 83%. Product sales, primarily DNA probe
products and genetic imaging workstations, increased by $4.7 million primarily
as a result of increased product shipments in the United States and Germany and
the incorporation of approximately nine months of operations in France and the
United Kingdom. Grant and other revenue in 1996 of $2.2 million consisted
primarily of $1.4 million earned in connection with the two United States
Department of Commerce grants and approximately $600,000 recognized pursuant to
the Fujisawa agreement. Grant and other revenue in 1995 of $900,000 included
$559,000 earned in connection with the two United States Department of Commerce
grants and approximately $300,000 recognized pursuant to the Fujisawa agreement.

Cost of goods sold increased to $5.5 million for the twelve months ended
December 31, 1996 from $4.0 million for the twelve months ended December 31,
1995. The increase in cost of goods sold resulted from an increase in the volume
of product sold. As a percentage of total revenue, gross profit increased from
44.3% during 1995 to 58.2% for 1996, primarily as a result of an increase in
grant and other revenue and as a result of a change in product sales mix toward
higher margin products.

Research and development expense increased to $9.5 million for the twelve
months ended December 31, 1996 from $8.9 million for the twelve months ended
December 31, 1995. The hiring of additional scientists in 1996 to support
development of the Company's three technology platforms and DNA probe products
accounted for a majority of the $600,000 increase.

Selling, general and administrative expense increased to $16.3 million for
the twelve months ended December 31, 1996 from $12.0 million for the twelve
months ended December 31, 1995. This increase was due to incremental general and
administrative expenses of $2.2 million primarily attributable to the hiring of
additional administrative personnel and other expenses incurred to support the
Company's growth and incremental selling expense of $2.1 million primarily due
to the hiring of additional sales and marketing personnel and other expenses
incurred in line with the overall expansion of operations.

Interest income in 1996 totaled $107,000 from Amoco based on the proceeds
from the sale of two facilities in Framingham, Massachusetts. Interest expense
in 1996 of $255,000 related to the note payable to Amoco.

TWELVE MONTHS ENDED DECEMBER 31, 1995 AND DECEMBER 31, 1994

Total revenue increased to $7.2 million for the twelve months ended December
31, 1995 from $5.4 million for the twelve months ended December 31, 1994, an
increase of $1.8 million or 33%. Product sales increased by $923,000, primarily
as a result of increased product shipments. Grant and other revenue in 1995
included $559,000 earned in connection with the two United States Department of
Commerce grants and approximately $300,000 recognized pursuant to the Fujisawa
agreement.

Cost of goods sold increased to $4.0 million for the twelve months ended
December 31, 1995 from $3.5 million for the twelve months ended December 31,
1994. The increase in cost of goods sold resulted from an increase in the volume
of product sales. As a percentage of total revenue, gross profit increased from
35.5% during 1994 to 44.3% for 1995, primarily as a result of an increase in
grant and other revenue and as a result of a change in product sales mix toward
higher margin products.

Research and development expense decreased to $8.9 million for the twelve
months ended December 31, 1995 from $11.6 million for the twelve months ended
December 31, 1994. The $2.7 million decrease

24
<PAGE>
reflected a more clearly defined research and development effort and the
consolidation of the Company's two research and development locations into one
facility.

Selling, general and administrative expense increased to $12.0 million for
the twelve months ended December 31, 1995 from $8.9 million for the twelve
months ended December 31, 1994. This increase was due to $2.8 million of
incremental general and administrative expenses primarily attributable to
additional litigation costs and $300,000 of additional selling expenses. See
"Business--Litigation."

INCOME TAXES

During the years ended December 31, 1994, 1995 and 1996, and during the nine
months ended September 30, 1997, the Company's results of operations were
included in the consolidated income tax returns of Amoco, accordingly, the
Company's domestic net operating losses have been utilized by Amoco in its
consolidated income tax returns and are not available to offset the Company's
future taxable income.

A full valuation allowance has been provided for all deferred tax assets
(net of liabilities) at September 30, 1997, as management does not consider
realization of such amounts more likely than not. On an unaudited pro forma
separate income tax return basis, assuming the Company was not included in the
consolidated income tax returns of Amoco, no tax provision or benefit would have
been recorded in the consolidated financial statements due to the ongoing losses
of the Company.

LIQUIDITY AND CAPITAL RESOURCES

Since inception, the Company has financed its operations primarily through
capital contributions and loans from Amoco. Capital contributions totaled $22.4
million, $15.4 million and $2.3 million for the years ended December 31, 1994,
1995 and 1996, respectively. Loans from Amoco totaled $10.1 million during the
year ended December 31, 1996 and $11.4 million during the nine months ended
September 30, 1997. The amounts due to Amoco under these loans have been reduced
by $5.0 million and $4.1 million, respectively, for the tax benefits recorded by
Amoco resulting from the inclusion of the Company's domestic net operating
losses in Amoco's consolidated income tax returns. Additional working capital
was provided as a result of the Company having sold, in January 1996, its two
facilities in Framingham, Massachusetts. Net sale proceeds totaled $6.7 million
and were sufficient to fund the Company's operations for the first five months
of 1996. The net amount due under the note payable to Amoco of $5.1 million at
December 31, 1996 was converted into 553,126 shares of Series B Preferred Stock
during September 1997. Amounts received under research grants and a distribution
agreement have provided cumulative funding of approximately 4.7 million through
September 30, 1997.

Net cash used in operating activities was $10.3 million for the nine months
ended September 30, 1997; $17.4 million, $11.3 million and $16.2 million for the
years ended December 31, 1996, 1995 and 1994, respectively. Cash used in
operating activities relates primarily to ongoing operating losses associated
with research and development of the Company's products and the development of a
sales and administrative infrastructure to support the Company's business plan.

Net cash used in investing activities was $0.9 million for the nine months
ended September 30, 1997; $3.4 million and $4.8 million for the years ended
December 31, 1995 and 1994, respectively, primarily relating to the purchase of
property and equipment. Net cash provided by investing activities was $4.7
million for the year ended December 31, 1996, primarily resulting from the sales
of two properties in Framingham, Massachusetts. The Company does not have any
current material commitments for capital expenditures.

Net cash provided by financing activities was $11.4 million for the nine
months ended September 30, 1997; $12.4 million, $14.9 million and $21.0 million
for the years ended December 31, 1996, 1995 and 1994, respectively, resulting
from capital contributions and loans received from Amoco.

25
<PAGE>
The Company has entered into various license agreements pursuant to which it
has been granted exclusive use of certain patented technologies. The agreements
require the Company to pay royalties ranging from 0.5% to 8.0% on net sales of
specified products, with certain minimum royalties due each year. As additional
consideration for certain of the licenses, the Company is obligated to fund
certain research of the licensors. Future minimum amounts due under all such
agreements range from $300,000 to $1.8 million per year for 1998 through 2002.
See Note 6 of Notes to Consolidated Financial Statements.

At September 30, 1997, the Company had cash of $294,000 and an accumulated
deficit of $26.5 million (post-recapitalization). Amoco intends to provide
financial support to the Company through the earlier of the completion of this
offering or December 31, 1998, which will result in an increase in the note
payable to Amoco. Amoco has advised the Company, however, that it does not
intend to continue such funding following the completion of the offering. The
Company has experienced negative cash flows from operations for the three years
ended December 31, 1996 and the nine months ended September 30, 1997. The
Company believes that the net proceeds from the offering, and the interest to be
earned thereon, will be sufficient to fund the Company's operations well into
1999. The Company's estimate of the time period for which cash funds will be
adequate to fund its operations is a forward looking estimate subject to risks
and uncertainty, and actual results may differ materially.

The Company's requirements for additional capital will depend on many
factors, including payments received under existing and potential collaborative
agreements; the availability of government research grant payments; the progress
of the Company's collaborative and independent research and development
projects; the costs of preclinical and clinical trials for the Company's
products; the prosecution, defense and enforcement of patent claims and other
intellectual property rights; and the development of manufacturing, sales and
marketing capabilities. To the extent capital resources, including payments from
existing and possible future collaborative agreements and grants, together with
the net proceeds of this offering are insufficient to meet future capital
requirements, the Company will have to raise additional funds to continue the
development of its technologies. There can be no assurance that such funds will
be available on favorable terms, or at all. To the extent that additional
capital is raised through the sale of equity or convertible debt securities, the
issuance of such securities could result in dilution to the Company's
shareholders. If adequate funds are not available, the Company may be required
to curtail operations significantly or to obtain funds through entering into
collaborative agreements on unattractive terms. The Company's inability to raise
capital as and when needed would have a material adverse effect on the Company's
business, financial condition and results of operations.

RECENT ACCOUNTING PRONOUNCEMENTS

In February 1997, the Financial Accounting Standards Board ("FASB") issued
SFAS No. 128 "Earnings Per Share," which establishes new standards for computing
and presenting earnings per share information. SFAS No. 128 will be effective
for the Company's 1997 annual financial statements. Reported pro forma net loss
per share data for 1996 and the nine months ended September 30, 1997 are the
same as that computed under the new standard.

In June 1997, the FASB issued SFAS No. 131 "Disclosures about Segments of an
Enterprise and Related Information." SFAS No. 131 establishes new standards for
reporting information about operating segments in interim and annual financial
statements. SFAS No. 131 will be effective for the Company in 1998. The Company
is currently evaluating the impact, if any, this statement will have on
disclosures in the consolidated financial statements.

26
<PAGE>
BUSINESS

INTRODUCTION

Vysis is a leading Genomic Disease Management company that develops,
commercializes and markets clinical products that provide information critical
to the evaluation and management of cancer, prenatal disorders and other genetic
diseases. The Company has assembled a management team experienced in developing,
commercializing and marketing DNA based diagnostic products and associated
genetic workstations. The Company was the first to obtain Food and Drug
Administration ("FDA") clearance for a genomic product using fluorescence IN
SITU hybridization ("FISH"). Vysis currently markets four FDA cleared clinical
products in addition to distributing over 240 research products through its
direct sales operations in the United States and Europe and a worldwide
distribution network covering 28 countries. It has an installed base of over 320
proprietary genetic workstations at 224 laboratories in 18 countries. The
Company has a pipeline of nine clinical products under development and an
expanding list of clinical product leads based upon its collaborations with
leading medical research institutions, which include the University of
California, San Francisco, the Mayo Clinic, St. Jude Children's Research
Hospital, the University of Chicago and the Reproductive Genetics Institute. The
Company's revenues have grown from $5.4 million in 1994 to $13.2 million in
1996. The Company's revenues for the first nine months of 1997 were $12.2
million compared to $9.0 million for the first nine months of 1996.

The Company's business represents the consolidation of multiple research
units and programs of Amoco. Over the past ten years, Amoco has invested over
$80 million to fund Vysis' research and development in nucleic acid technologies
and related business operations. As a result of this investment, Vysis has
compiled a broad portfolio of intellectual property and expertise, which forms
the basis of its core technologies. Vysis owns or has an exclusive license to 92
issued United States patents or allowed United States patent applications, and
69 pending United States patent applications that protect its core technologies,
diagnostic platforms and genetic targets. Upon completion of this offering,
Amoco will beneficially own approximately 63% of the Company's outstanding
Common Stock.

27
<PAGE>
syndrome, sex chromosome abnormalities and two additional chromosomal
abnormalities, which together account for 85% to 90% of chromosomal causes of
mental retardation and other birth defects, was cleared by the FDA as a 510(k)
in October 1997 and its marketing has begun.

SCIENTIFIC OVERVIEW

Genetic abnormalities are a fundamental source of human disease. Genetic
based diseases and disorders include cancer, birth defects, mental retardation,
coronary artery disease, autoimmune diseases and diabetes. Genomic Disease
Management is an emerging field that uses new genetic tests based on
correlations between genetic abnormalities and disease. Genomic Disease
Management products, by providing new information not currently available
through existing methods, enable physicians to diagnose disease more quickly and
accurately, to determine the most appropriate treatment and to monitor disease
progression and recurrence during therapy. Genomic Disease Management products
also enable the detection of disease at the very early or developing stages when
treatment is likely to be most effective. In addition, Genomic Disease
Management products allow physicians to identify genetic predisposition to
disease well before the disease is manifested, thus enabling early intervention
either through lifestyle changes or preventive therapy.

The genetic code, consisting of DNA, contains all the information necessary
for any organism to develop and function. The information is encoded in the
specific sequence of DNA's four nucleotide bases: Adenine, Thymine, Cytosine and
Guanine. These units, or "bases," are strung together like beads on a string.
DNA is a double-stranded molecule composed of two single strands entwined around
the other in the form of a double helix. The bases of one strand always bind to
the bases of the other in a specific fashion: A pairs with T, and C with G. This
pairing of bases is referred to as base pairs.

STRUCTURE OF HUMAN GENETIC INFORMATION

[GRAPHIC]

HUMAN DNA IS CONTAINED IN 46 CHROMOSOMES AND EACH CHROMOSOME HAS, ON AVERAGE,
5,400 GENES. AN AVERAGE GENE IS BUILT FROM A SEQUENCE OF 24,000 NUCLEOTIDE BASES
(A, T, G, C), THE MOST FUNDAMENTAL PART OF A GENE. GENETIC DISEASE CAN BE
ASSOCIATED WITH A LARGE CHROMOSOMAL ABNORMALITY, SUCH AS A MISSING OR EXTRA
CHROMOSOME; WITH A GENE ABNORMALITY, SUCH AS GENE DELETION OR AMPLIFICATION OR
WITH A SINGLE NUCLEOTIDE ABNORMALITY, SUCH AS A BASE PAIR MUTATION.

28
<PAGE>
Cells carry out their normal biological functions through the genetic
instructions encoded in their DNA. This process, known as gene expression,
involves several steps. In the first step, bases in a gene are copied into a
related nucleic acid molecule called messenger ribonucleic acid ("mRNA"). In the
second step, mRNA instructs the cells to produce proteins. Proteins are
molecules that regulate or perform most of the physiological functions of the
body. Because the order of bases in each gene is different, each gene directs
the production of a different protein. Each organism's characteristics are,
therefore, ultimately determined by proteins encoded by its DNA.

Aberrations in the genetic code, that is, changes in the arrangement of the
nucleic acid bases, can cause a wide range of diseases and defects. Some genetic
diseases are manifested by "gross changes" at the chromosomal level such as an
extra copy (a "trisomy") of an entire chromosome, e.g., Down syndrome; a missing
("deleted") or extra ("duplicated") part of a chromosome, e.g., Cri-du-chat
syndrome; or different chromosomes exchanging parts or combining (a
"translocation"), e.g., the bcr/abl translocation causing chronic myelogenous
leukemia ("CML"). Some diseases are associated with an abnormal number of a
particular gene ("gene amplification") such as the HER-2/neu gene amplification
exhibited in some forms of breast cancer. Other genetic-related diseases or
defects are caused by changes at a more minute level, such as a change in the
sequence of only a few base pairs, e.g., the change at location 508 in the
cystic fibrosis ("CF") gene as evidenced in certain cases of CF, or a change in
only one base pair, known as a point mutation, e.g., sickle cell disease.

A principal method of detecting genomic abnormalities in medical research is
through the use of DNA probes. DNA probes are designed to identify the presence,
absence or location of a particular target sequence by hybridization or the
failure to hybridize to the particular target sequence. A DNA probe is a
particular single stranded piece of DNA or RNA, which is configured to have the
specific sequence of bases, which is complementary to, and thus will bind to a
specific target sequence. This binding of two complementary nucleic acid strands
is called "hybridization." The DNA probe and the sample DNA or RNA extracted
from or in a cell are mixed under conditions which permit the probe to hybridize
to its target. The DNA probes are generally labeled with markers, such as
fluorescent molecules, to permit their detection upon hybridization. The
unreacted probe is washed away and the mixture is then examined to detect the
presence of the label on the hybridized probe.

TECHNOLOGY PLATFORMS

Genomic Disease Management requires the ability to assess abnormalities of
chromosomes, individual genes within chromosomes and specific DNA sequences
within genes. No single technology is capable of assessing all of these
different types of abnormalities. To address this issue, the Company has
developed three complementary technology platforms that detect the full range of
genetic abnormalities from large chromosomal aberrations to smaller
abnormalities associated with abnormal numbers of the same gene and the smallest
mutations within specific gene sequences. The Company believes these
complementary technologies will enable the clinician to provide a comprehensive
approach to genomic assessment in the management of disease.

Vysis' three technology platforms include: the FISH SYSTEM, which detects
chromosomal copy number and rearrangement (large genetic structures), the
GCGH-TM- ARRAY SYSTEM, which detects gene copy number and expression (smaller
genetic structures), and the MOLECULAR LAWN-TM- SYSTEM, which detects specific
gene sequences and their mutations (smallest genetic structures). Each platform
provides the advantage of being able to simultaneously detect multiple genetic
abnormalities in the same specimen. Vysis expects to introduce a broad range of
products based on each of these platforms. This product development strategy is
expected to reduce time to market and associated development costs for each
product. Each of these three technology platforms also relies upon the Company's
image analysis software, which is comprised of proprietary algorithms that
enable the automated display and analysis of FISH, gCGH Array and Molecular Lawn
tests.

29
<PAGE>
FISH SYSTEM

The FISH System provides the ability to simultaneously assess multiple
chromosomal and gene abnormalities in a single intact cell. FISH also provides
the ability to perform cell by cell quantitative assessment of genetic changes
in tissue specimens routinely used by pathologists for diagnosis. The Company's
FISH System consists of instruments and image analysis workstations used with
the Company's patented direct label FISH probes.

FISH, illustrated in the figure below, is generally faster, easier-to-use
and more cost-effective than alternate technologies. FISH assays test the DNA of
a sample while in its native setting in the cell ("IN SITU") and thus provide
genomic assessment on intact cells. Alternate technologies destroy surrounding
tissue and cells resulting in the loss of valuable diagnostic information. FISH
probes can be used to detect chromosomal abnormalities present in "interphase
cells" commonly found in tissues processed in pathology laboratories. This
eliminates the time-consuming culture of tissue to obtain metaphase cells, which
in the case of many solid tumor cancers is difficult, if not impossible. FISH
technology provides clinical information on certain genetic abnormalities in
interphase cells not obtainable with any other techniques known to the Company.

DIRECT LABEL FISH TECHNOLOGY

[GRAPHIC]

FISH: SLIDES WITH TISSUE SPECIMENS ON THEM, SIMILAR TO THOSE USED IN ROUTINE
PATHOLOGY LABORATORIES FOR CLINICAL DIAGNOSIS, ARE HYBRIDIZED WITH FLUORESCENTLY
LABELED FISH PROBES. WITH THE USE OF A FLUORESCENCE MICROSCOPE, A GENETICIST OR
PATHOLOGIST IS ABLE TO SEE CHROMOSOMAL AND GENE ABNORMALITIES IN THE NUCLEUS OF
INDIVIDUAL CELLS ON THE SLIDE. (FLUORESCENT LABEL ATTACHMENT POINT NOT SHOWN)

30
<PAGE>
FISH uses DNA probes that are large, typically at least 30,000 base pairs in
length. Consequently, FISH is useful primarily to detect gross or large
chromosomal changes, such as extra chromosomes, missing chromosomes, chromosomal
translocations, and gene amplifications and deletions.

Vysis' FISH technology uses its patented direct label DNA probes. The
Company has pioneered the use of direct label FISH probes and the high-quality,
reproducible manufacture of these probes. Vysis believes that its direct label
FISH probes are superior to other probes because they produce sharper and
brighter fluorescent signals and decrease assay time by eliminating procedural
steps and reagents which are required with indirect label probes. All of these
benefits produce results that are easier to obtain and interpret.

FISH provides the unique ability to simultaneously assess multiple
chromosomal and gene abnormalities in a single intact cell. Currently as many as
seven different FISH probes can be identified in a single interphase cell with
the Company's multi-color direct label technology. This provides physicians with
the ability to detect multiple genetic aberrations in the same cell, which is
important for certain cancers and prenatal birth defects. The Company is not
aware of any other molecular diagnostic technology that has this capability.

Vysis has developed and is continuing to refine instruments and image
analysis workstations used in conjunction with the Company's direct label FISH
probes. The Company's HYBrite-TM- instrument automates the hybridization process
in a temperature controlled environment. The Company's Quips Genetic
Workstations provide integrated solutions to enhance and automate the
visualization, analysis, and storage of FISH images. The Company is currently
undertaking development of a high throughput instrument that will automate both
specimen preparation and the hybridization process. This development program and
subsequent manufacturing is expected to be completed in conjunction with an
outside engineering firm.

GCGH-TM- ARRAY SYSTEM

The gCGH Array System uses the Company's patented comparative genomic
hybridization ("CGH") technology to survey the entire genome for chromosomal
changes in a single test. The fundamental principle of CGH is to compare an
abnormal or test DNA (or RNA) specimen to a reference DNA (or RNA) in order to
detect genetic aberrations. This method, like the FISH System, does not require
culturing of "metaphase cells" for a metaphase spread preparation from the
sample. For this reason, CGH enables genetic testing of tissues that are not
amenable to culture such as tumor tissues. In contrast to traditional FISH
technology that typically involves use of a specific probe to a known
chromosomal abnormality, CGH can be used to investigate an entire genome even
when a suspected genetic aberration is unknown.

31
<PAGE>
Vysis is developing a ready-to-use array of DNA probes on a miniaturized
chip ("gCGH array") which incorporates its patented CGH technology. Each element
of the array will contain DNA from a defined location on a normal human
chromosome and, in total, the collection of elements may represent the entire
genome. This system is intended to enable simultaneous assessment of a large
number of genes in a patient's specimen for abnormalities in the specific gene
count. An example of a gCGH array is shown below.

GCGH ARRAY SYSTEM

[GRAPHIC]

GCGH ARRAY: PATIENT DNA, LABELED WITH A GREEN (BLACK IN THE PICTURE),
FLUORESCENT MOLECULE, IS MIXED WITH NORMAL REFERENCE DNA, LABELED WITH A RED
FLUORESCENT MOLECULE (WHITE IN THE PICTURE), AND APPLIED TO A GCGH ARRAY
CONTAINING 10'S TO 1,000'S OF INDIVIDUAL GENE TARGETS. UPON COMPLETION OF THE
REACTION, THE GCGH ARRAY IS READ BY MEASUREMENT OF THE RATIO OF GREEN TO RED
FLUORESCENT LIGHT AND THE RESULTS REPORTED, INDICATING WHETHER THE PATIENT DNA
HAS TOO MANY OR TOO FEW COPIES OF A PARTICULAR GENE.

By allowing the simultaneous assessment of abnormalities in multiple genes
associated with cancer, the Company believes that the use of gCGH arrays will
allow the clinician to more reliably select the most effective treatment for
cancer patients and will also provide important prognostic information. The
Company also believes that gCGH arrays will simplify determination of prenatal
abnormalities by the simultaneous detection of chromosome aneusomies,
microdeletions and unbalanced chromosome translocations. These abnormalities may
account for essentially all of the causes of common mental retardation and other
birth defects detectable with conventional amniocentesis and karyotyping. The
Company expects that the automation possible with arrays will improve the
reliability and accuracy of diagnosis, reduce the time to obtain the result and
reduce the cost for prenatal testing. The Company further believes that

32
<PAGE>
gCGH arrays will be applicable to the determination of gene expression which may
provide an indication of early disease manifestation.

The gCGH Array System, consisting of individual arrays, a high speed camera
based reader and specimen processing reagents is currently at the prototype
stage of development. The Company currently has the capability of manufacturing
research quantities of gCGH Arrays and is developing a high throughput robotic
system for production of commercial quantities of arrays.

MOLECULAR LAWN SYSTEM

The Molecular Lawn System uses the Company's patented Q-beta replicase
("QBR") amplification technology to detect specific gene sequences. QBR provides
a quantitative measure of a specific gene sequence in either human, viral or
bacterial DNA. Because the Molecular Lawn is a self contained system and is
being specifically designed for clinical use, this QBR based product is intended
to provide a more accurate, simple and cost-effective alternative to other
amplification technologies such as polymerase chain reaction ("PCR"). This
technology platform enables the detection of small genetic targets associated
with disease predisposition and early detection of disease. The system includes
a disposable test device and an automated reader that will provide both
qualitative and quantitative results. The Company's initial product will be
designed for the detection of Human Papilloma Virus ("HPV"), which causes
cervical cancer.

A Molecular Lawn consists of individual or multiple probe sequences attached
to the surface of a miniaturized solid support, similar to the blades of grass
on a lawn (see figure below).

MOLECULAR LAWN SYSTEM

[GRAPHIC]

MOLECULAR LAWN: PATIENT SPECIMEN IS PLACED ON THE MOLECULAR LAWN, CONTAINING
HALF PROBE MOLECULES. THE SECOND HALF OF THE PROBE MOLECULES ARE THEN PLACED ON
THE SURFACE OF THE MOLECULAR LAWN CONTAINING THE CAPTURED DNA IN THE PATIENT
SPECIMEN. IF A PARTICULAR HUMAN, VIRAL OR BACTERIAL DNA EXISTS IN THE PATIENT
SPECIMEN, A SIGNAL WILL BE GENERATED BY QBR. IF THE PARTICULAR HUMAN, VIRAL OR
BACTERIAL DNA BEING TESTED FOR DOES NOT EXIST, A SIGNAL WILL NOT BE PRESENT.

33
<PAGE>
PRODUCTS

CLINICAL DIAGNOSTIC PRODUCTS

Vysis is developing, commercializing and marketing clinical products that
provide information critical to the evaluation and management of cancer,
prenatal disorders and other genetic diseases. Having already received four FDA
approvals for its reagent products via the 510(k) process, the Company has
established a track record of successfully obtaining required regulatory
clearances for its products. As advances in molecular biology lead to the
discovery of additional correlations between genetic mutations and disease, the
Company believes that it is well positioned to take advantage of these
developments and the resulting increase in market demand for Genomic Disease
Management products. The Company's clinical diagnostic product commercialization
process involves four distinct stages prior to marketing which include, in
order, research, development, clinical trials and regulatory review.

CLINICAL PRODUCTS

<TABLE>
<CAPTION>
PRODUCT TECHNOLOGY PLATFORM DISEASE/PROCEDURE INTENDED UTILITY STAGE
- ----------------- --------------------- ----------------- ----------------- ------------
<S> <C> <C> <C> <C>

CANCER
CEP-Registered Trademark- FISH System Chronic Disease MARKETING
8 Myelogenous monitoring (FDA 510(k)
Leukemia, myeloid cleared
disorders November
1996)

CEP-Registered Trademark- FISH System Chronic Disease MARKETING
12 Lymphocytic progression and (FDA 510(k)
Leukemia disease cleared
monitoring January
1997)

CEP-Registered Trademark- FISH System Bone marrow Disease MARKETING
X/Y transplantation monitoring (FDA 510(k)
cleared
January
1997)

HER-2/neu FISH System Breast cancer Selection of CLINICAL
therapy and TRIALS
prognosis

bcr/abl ES FISH System Chronic Diagnosis and DEVELOPMENT
Myelogenous disease
Leukemia monitoring

Breast Panel gCGH Array System Breast cancer Selection of RESEARCH
therapy and
prognosis

Bladder Panel FISH System Bladder cancer Disease RESEARCH
recurrence
monitoring

Prostate Panel gCGH Array System Prostate cancer Disease RESEARCH
progression

Human Papilloma Molecular Lawn System Cervical cancer Early disease RESEARCH
Virus Panel detection
</TABLE>

34
<PAGE>
CLINICAL PRODUCTS (CONTINUED)

<TABLE>
<CAPTION>
PRODUCT TECHNOLOGY PLATFORM DISEASE/PROCEDURE INTENDED UTILITY STAGE
- ----------------- --------------------- ----------------- ----------------- ------------
<S> <C> <C> <C> <C>

PRENATAL
TriGen-TM- Panel FISH System Down syndrome, Detection of MARKETING
sex chromosome mental (ADM
disorders retardation and registered
other birth in France
defects June 1997)

AneuVysion-TM- FISH System Down syndrome, Detection of MARKETING
and other mental (FDA 510(k)
chromosomal retardation and cleared
disorders other birth October
defects 1997)

Aneu-Del-Tel-TM- gCGH Array System Down syndrome, Detection of RESEARCH
Chip and other essentially all
chromosomal chromosomal
disorders abnormalities
causing common
mental
retardation and
other birth
defects

Fetal Screen FISH System Down syndrome, Detection of RESEARCH
and other mental
chromosomal retardation and
disorders other birth
defects from
fetal cells in
maternal blood
circulation
</TABLE>

CANCER PRODUCTS

The American Cancer Society estimates that approximately 1.4 million people
in the United States were diagnosed with some form of cancer in 1997.
Approximately $35 billion is spent annually in the United States alone on direct
medical costs in managing cancer patients. For most cancers, five year survival
rates increase by a factor of up to 100% if diagnosed and treated in a localized
state; however, only 54% of breast cancers, 57% of prostate cancers and 51% of
cervical cancers are detected in a localized state.

In the management of patients with cancer, there is an unmet clinical need
for tests that will diagnose disease at an earlier stage, predict therapeutic
response to chemotherapy and monitor patients for disease recurrence at an
earlier stage. Vysis' initial Genomic Disease Management cancer products are
expected to enable selection of the best possible therapy and thereby improve
patient survival rates and quality of life. The Company is directing its product
development and commercialization efforts toward various cancers including
leukemia, breast, bladder, prostate and cervical.

LEUKEMIA. There are four primary forms of leukemia with an estimated
aggregate of 27,600 new cases in 1996, approximately evenly divided between
acute leukemia and chronic leukemia. CML accounts for approximately one-fourth
of all leukemia cases, with an incidence of approximately 1 case per 100,000
persons. In the United States, there are about 6,000 newly diagnosed patients
each year. The disease has two major phases: the initial chronic phase and the
terminal blast crisis phase. The transition from chronic to blast phase is often
associated with abnormal occurrence of three copies of chromosome 8 (trisomy 8)

35
<PAGE>
which is present in approximately 20% to 50% of those patients entering the
blast phase. This abnormality often precedes the clinical blast phase by 2 to 6
months. The success rate of long term survival following bone marrow
transplantation is less than 20% for patients in blast crisis as compared to a
40% to 70% success rate for patients treated before the onset of blast crisis.
The detection of trisomy 8 in conjunction with other tests may serve as an early
indication to initiate bone marrow transplantation when the patient has a better
chance for survival.

The Company's first clinical product, CEP 8 Probe Kit, which is based on the
FISH System, was cleared by the FDA in November 1996 by a 510(k) premarket
notification. The CEP 8 Probe Kit is used for the detection of trisomy 8. Used
in conjunction with other tests, this product is used to monitor disease
activity during treatment to assess therapeutic effectiveness and during
remission for disease recurrence. This information provides the physician with
an indication of early blast crisis which is important when considering bone
marrow transplantation therapy.

The Company's second clinical product, CEP 12 Probe Kit, which is based on
the FISH System, was cleared by the FDA in January 1997 by a 510(k) premarket
notification. The CEP 12 Probe Kit is used for the detection of trisomy 12, one
of the more common genetic abnormalities in chronic lymphocytic leukemia
("CLL"). The incidence of CLL in the United States is approximately 7,200 new
cases per year with about 60,000 individuals currently afflicted with this
disease. These patients have a widely variable clinical course and many do not
require therapy at the time of diagnosis. The detection of trisomy 12 provides
the physician the ability to distinguish patients whose disease will rapidly
progress. These patients may require immediate treatment while others may be
monitored for disease progression without therapeutic intervention.

The Company's third clinical product, CEP X/Y Probe Kit, which is based on
the FISH System, was cleared by the FDA in January 1997 by a 510(k) premarket
notification. The CEP X/Y Probe Kit is used to assess how well donor cells are
accepted by the recipient in sex-mismatched bone marrow transplantation and to
determine the recurrence of malignant cells. In the management of many leukemias
and other myeloid disorders, bone marrow transplantation is a critical
therapeutic strategy. Approximately 4,200 sex-mismatched transplantations were
performed in the United States in 1996. Having an estimate of the proportions of
donor and recipient cells following a transplanation can be useful in assessing
the success of the procedure and to diagnose recurrence. The improved
sensitivity and precision of the CEP X/Y product, as compared to standard
cytogenetic analysis, permits a more reliable detection of therapeutic efficacy
or failure at a stage when modification of therapy will still be possible.

A fourth product, a bcr/abl translocation probe currently under development,
is expected to be submitted for regulatory review in the United States and
Europe. The bcr/abl ES product, which is based on the FISH System, is intended
to be used to confirm the diagnosis of CML and to monitor the presence of
residual disease.

BREAST CANCER. Breast cancer is the second leading cause of cancer-related
deaths among women age 35 to 54. In 1996 there were approximately 184,300 new
cases of breast cancer diagnosed in the United States. Over 900,000 biopsies to
determine the presence of breast cancer are performed in the United States each
year. According to the American Cancer Society, the annual direct medical cost
of breast cancer management in the United States alone is approximately $6
billion.

The management of breast cancer is difficult because there has been no
reliable method to determine the response of individual women to different
therapeutic options, each of which have different toxicities and side-effects.
These toxicities and side-effects impact the quality of life and long term
survival of individual patients. It is clearly beneficial to identify which
women have progressive disease and to restrict aggressive treatment to that
group. The specific genetic abnormalities of a tumor are associated with
progressive disease and therapeutic response. A genomic test that adds to the
physician's ability to select the most appropriate therapy during clinical
decision-making and that results in a more favorable outcome for the patient
would be highly valued.

36
<PAGE>
The Company's first breast cancer product, currently in late stage clinical
trials, is HER-2/neu. Results from the HER-2/neu test are intended to rapidly
assess the amplification of HER-2/neu gene for use as a predictive marker for
response to chemotherapy and/or hormone therapy. Results will also be used as a
prognostic marker for risk assessment.

HER-2/neu is an oncogene whose normal function is to serve as a growth
factor receptor. Amplification of this gene is associated with rapid growth of
the tumor cells and resistance to less toxic chemotherapy and/or hormone
therapy. Approximately 25% to 30% of breast cancers have amplification of this
gene. A study of 442 breast cancer patients, published in the NEW ENGLAND
JOURNAL OF MEDICINE in May 1994, supports the use of HER-2/neu gene
amplification as a predictive marker for response to chemotherapy. This study
demonstrated that lymph node positive women with HER-2/neu amplification in
their tumor cells respond to higher doses of adriamycin chemotherapy
substantially better than those without amplification. Further, patients without
amplification do not appear to benefit from the more aggressive adriamycin
treatment. The ability to identify amplification in breast cancer patients will
allow such patients to be more effectively treated with aggressive chemotherapy,
which in turn should produce better patient outcomes. Additionally, those
patients who are not amplified do not require the more aggressive chemotherapy
and may benefit from an improved quality of life by avoiding the side effects
inherent with the more aggressive therapeutic approach. Another study at
Georgetown University's Lombardi Cancer Center on 94 breast cancer patients
indicates that women with HER-2/neu amplified tumors respond more poorly to
hormone therapy than women without amplification.

The Company's HER-2/neu product, which is based on the FISH System, is a
locus specific, direct label DNA probe for the HER-2/neu gene. This assay is
designed for the detection and quantification of the HER-2/neu gene and
chromosome 17 in cells. Occasionally, extra copies of the chromosome 17 will
result in a false positive HER-2/neu result. The Company's product includes a
second DNA probe specific for chromosome 17, which is intended to serve as a
built in control for false positive results due to extra copies of chromosome
17. The Company, in collaboration with independent laboratories, conducted
performance studies of the Company's HER-2/neu gene product which indicate that
the product may be able to detect HER-2/neu amplification in 50 percent more
women with breast cancer than detected by antibody based immunohistochemistry in
standard paraffin tissue sections.

Vysis expects that this product will provide reliable and accurate
determination of HER-2/neu gene amplification to physicians to assist them in
selection of the most appropriate therapeutic alternatives for the patient. The
product's initial claim will be for prediction of response to low or high dose
adriamycin therapy. Adriamycin and its equivalents are among the most commonly
used cancer therapeutics.

The Company's strategy is to maximize value to the medical community by
expanding the utility of the HER-2/neu product through supplemental clinical
trials. These trials include studies to determine selection of therapy between
methotrexate and adriamycin based on HER-2 amplification, to determine whether
the patient will benefit from hormone therapy and to predict the risk that
benign breast lesions will progress to cancer.

Because cancer is considered a multi-gene event, the Company believes that
appropriate patient management may require simultaneous testing for multiple
genetic abnormalities, such as amplification of the c-myc gene, the Cyclin D1
gene and the q13.2 region on chromosome 20 in addition to HER-2/neu. The Company
is developing products based on the Company's gCGH Array System which are
intended to provide the ability to simultaneously detect both gene amplification
abnormalities and gene deletion abnormalities, such as deletion of the p53 tumor
suppressor gene.

BLADDER CANCER. The American Cancer Society estimates there were
approximately 52,900 new cases of bladder cancer in 1996. The most common
symptom of this cancer is blood in the urine, which occurs in approximately 80%
of diagnosed patients. The diagnosis of a tumor often is confirmed by performing
urine cytology, which has a false negative rate of about 25%. Due to poor
sensitivity of cytology and other existing tests, examination of the bladder
wall with a cystoscope, a slender tube fitted with a lens and light that is
inserted through the urethra, is required to confirm the presence of bladder
cancer.

37
<PAGE>

Bladder cancer can be divided into superficial and invasive tumors.
Superficial tumors have not grown through the wall of the bladder to its
muscular lining. While the majority of tumors are superficial and are associated
with a high five-year survival rate (75% overall), approximately 80% of the
superficial tumors will recur. The most successful treatments are performed
early in the course of the diagnosis and include regular monitoring for disease
recurrence through the frequent use of cystoscopy. While cystoscopy will provide
definitive results, it is an invasive procedure requiring that the patient be
under anesthesia and is therefore expensive, costing over $500 per procedure.
Tests are currently on the market which will provide a result from a urine
specimen. However, these tests are relatively insensitive, detecting only 40% to
70% of positive specimens. For this reason, patients continue to have cystoscopy
procedures 1 to 4 times per year. The Company believes that a non-invasive
genomic test with high sensitivity and specificity that enables physicians to
easily monitor patients on a quarterly basis for disease recurrence would be
highly valued.

The Company is developing a highly sensitive product based on the FISH
System technology platform intended to provide simultaneous analysis of multiple
genetic markers for bladder cancer from a routine urine specimen. A number of
published studies have demonstrated that these genetic markers are correlated to
bladder cancer.

PROSTATE CANCER. Prostate cancer is the second leading cause of death from
cancer in men in the United States with an estimated 317,100 new cases in 1996.
Between 1989 and 1993, prostate cancer incidence rates increased 50%. Further
increased incidence detection is expected with continuing widespread use of
prostate serum screening tests. The incidence of prostate cancer increases with
age; over 80% of all prostate cancers are diagnosed in men over age 65. The
American Cancer Society recommends that men age 50 and over have an annual PSA
(prostate specific antigen) blood test and a digital rectal exam. If either
result is suspicious, further evaluation is recommended. This has resulted in
over 725,000 prostate biopsies being performed in the United States in 1996.
According to the American Cancer Society, the annual direct medical cost of
prostate cancer management in the United States alone is approximately $5
billion. The management of prostate cancer is difficult because its course is
extremely variable. Some prostate cancers grow rapidly, quickly leading to
death, while others grow so slowly as not to compromise expected life duration.
It is estimated that approximately 30% of men who die over the age of 45 from
various causes also have concurrent asymptomatic prostate cancer. Because there
is no reliable method to determine which cancers will progress, patients are
currently receiving unnecessary radical prostatectomies which have significant
side effects, which may negatively impact the quality of life. Side effects of
radical prostatectomy include impotence in about 30% of cases, bladder
incontinence in 10% to 20% of cases and difficulty with urination in about 10%
of cases. It is clearly beneficial to identify which men have progressive
disease and to restrict aggressive treatment to that group. A genomic test that
adds to the physician's ability to determine which patients to treat versus
which patients to monitor has been identified as highly desirable by the medical
community.

The Company believes that information regarding the genetic composition of
prostate cancer tumors could distinguish between men who should be monitored
without surgical intervention and those whose prostates should be removed. The
Company is developing a product that includes a panel of genetic markers
designed to provide information indicating which patients should receive more
aggressive therapeutic intervention. Because prostate cancer is also considered
a multi-gene event, the Company believes that appropriate patient management
will require simultaneous testing for multiple genetic abnormalities. Products
based on the Company's gCGH Array System are intended to provide the ability to
simultaneously detect both gene amplification abnormalities and gene deletion
abnormalities, each of which have been associated with disease progression. In
conjunction with the Mayo Clinic, the Company is evaluating several potential
leads for its initial gCGH Array product panel.

CERVICAL CANCER. An estimated 15,700 cases of invasive cervical cancer were
diagnosed in the United States in 1996 with an estimated 4,900 cervical cancer
deaths. Eighty-eight percent of patients survive one year after diagnosis, and
the five-year relative survival rate is 68%. However, for women diagnosed in the

38
<PAGE>
early stages of the disease, the five-year survival rate is 91%; but only 51%
are diagnosed in the early stages of the disease.

The American Cancer Society recommends that women who are, or have been,
sexually active or who have reached age 18, have an annual pelvic exam and a PAP
test. Approximately 62 million PAP tests are performed annually in the United
States at an estimated patient cost of $7 to $15 per test. Although PAP testing
has been useful in reducing deaths due to cervical cancer, the PAP test has
significant limitations. PAP testing has a false negative rate of 10% to 50% and
a false positive rate of 1% to 10%. A false-negative test means that a true
carcinoma has escaped detection and may advance to potentially irreversible
disease before an accurate test is performed. A false-positive result can lead
to unwarranted patient anxiety as well as unnecessary inconvenience, discomfort,
and expense for follow-up diagnostic procedures. Given the frequency of false
positive and false negative tests, the Company estimates that each year there
are about 5 million inaccurate test results. Positive PAP test results are
typically confirmed by a second PAP test, a colposcopy costing the patient
approximately $150, or cryosurgery costing approximately $500.

According to the American Cancer Society and the National Institutes of
Health ("NIH"), cervical cancer risk is closely linked to certain types of HPV,
a common sexually transmitted infection. Studies have shown that several types
of HPV have been directly implicated as a cause of cervical cancer. Furthermore,
there is a delay between HPV infection and the earliest manifestation of cancer.
The Company believes that a test specific for HPV performed in conjunction with
PAP testing would significantly improve the rate of early detection of cervical
cancer.

Vysis is developing a product for the simultaneous detection of specific
high and low risk types of HPV based on the Company's Molecular Lawn System
technology platform. The initial product application will be to test patient
specimens classified as atypical with PAP testing. The Company expects that this
product would be introduced as a patient screening test performed in conjunction
with a PAP test. The Company believes this product will be easier to use and
more cost effective than currently available technologies.

Additionally, the Company believes that assessing changes in the genetic
composition of cervical cells will also be important for the early
identification of cells in a pre-cancerous state. Combined with HPV testing,
genetic screening has a high potential for accurately predicting malignant
transformation not currently possible. The Company is assessing potential
genetic targets to be combined with its HPV tests.

PRENATAL PRODUCTS
Each year there are approximately 4 million live births in the United States
and a similar number in Western Europe. Chromosomal disorders are relatively
common affecting approximately 1 in 200 births. This has led to efforts to
perform screening to identify pregnancies at risk for fetal mental retardation
or other birth defects. In an attempt to diagnose fetal abnormalities, indirect
tests have been employed such as the immunoassay based blood tests known as the
"Triple Screen." Indirect testing has a high rate of false positive and false
negative results. Because of the inadequacies of indirect testing, a more
definitive genetic test is required to confirm the presence of fetal
abnormalities. To perform direct genetic testing, it is necessary to obtain
fetal cells. These cells may be obtained either through sampling the fluid
surrounding the fetus (amniocentesis), chorionic villus sampling, or potentially
through isolation of fetal cells that have crossed the placenta and are
circulating in the mother's blood. Pregnancies at high risk for chromosomal
abnormalities include women over age 35, a family history of chromosome
abnormalities, an abnormal Triple Screen result or abnormal ultrasound results.

AMNIOCENTESIS TESTING. Amniocentesis is an invasive procedure required to
obtain the fetal cells for diagnosis of chromosomal abnormalities. In
amniocentesis, amniotic fluid containing fetal cells is removed from the uterus
with an ultrasound-guided needle passed through the abdominal wall. Traditional
testing of the fetal cells is accomplished by direct visualization of stained
chromosomes. This analysis, which is known as karyotyping, is a standard
cytogenetic method which requires 7 to 10 days for completion at an estimated
patient cost of $400 to $800 per analysis. The Company believes that a genomic
test which

39
<PAGE>
provides rapid test results for chromosomal abnormalities enabling timely
decisions regarding patient treatment and care would be highly valued by
expecting parents and physicians.

The Company's first prenatal diagnostic product, based on the FISH System,
is the TriGen Assay for the direct diagnosis of Down syndrome (three copies of
chromosome 21) and sex chromosome abnormalities (aneuploidies of chromosomes X
and Y). The product is designed to diagnose these abnormalities on a single
slide within 24 hours from cells obtained by amniocentesis. Clinical trials
conducted by the Company at 18 laboratories involving 558 patients demonstrated
100% correlation of TriGen results to standard karyotyping results. The French
regulatory agency, Agence du Medicament ("ADM"), registered the product in May
1997, as a stand alone diagnostic test.

In December 1996, France became the first country to provide reimbursement
for testing of chromosome 21 disorders for all pregnancies regardless of age.
The French Cytogenetics Society has recommended to the French government a
reimbursement rate specifically for a FISH based prenatal test of approximately
$425 per test.

The Company's AneuVysion-TM- product is a FISH System for the direct
diagnosis of Down syndrome, sex chromosome abnormalities and two additional
chromosomal abnormalities. The Company's 510(k) submission on its AneuVysion
prenatal product was cleared by the FDA in October 1997 and a submission was
made to the French ADM in October 1997. Clinical trials conducted by the Company
at 31 laboratories involving 1,516 patients demonstrated 99.9% correlation of
AneuVysion results to standard karyotyping for those chromosomal abnormalities
that represent 85% to 90% of the chromosomal abnormalities associated with
mental retardation and other birth defects. In the United States, the AneuVysion
product is cleared as an adjunct to standard cytogenetic testing of
amniocentesis specimens while in Europe the Company expects the product to be
registered as a stand alone diagnostic test.

The Company is developing a gCGH Array prenatal product that is intended to
simultaneously detect multiple chromosome aneusomies, microdeletions and
unbalanced chromosome translocations. These abnormalities may account for
essentially all of the causes of common mental retardation and other birth
defects detectable with conventional amniocentesis and karyotyping.

MATERNAL BLOOD TESTING. Due to the invasive nature of the amniocentesis
procedure, current prenatal genetic testing is indicated only in high risk
pregnancies. Although the risk of having a child with Down syndrome increases
with maternal age, most pregnancies occur in younger women and, hence, most
births of children with Down syndrome occur to younger women for whom
amniocentesis is not indicated. The ability to detect and analyze fetal cells in
maternal blood would permit women to be routinely screened for genetic
abnormalities associated with mental retardation and birth defects by direct
genetic analysis of fetal cells.

Maternal blood has been shown to contain cells derived from the fetus,
although these cells are exceedingly rare. The feasibility of genetic analysis
of fetal cells isolated from maternal blood has been demonstrated, but obtaining
a sufficient number of fetal blood cells for analysis has been difficult and
generally not suitable to routine clinical application. Vysis is currently
researching a system to identify fetal cells in maternal blood specimens and
detect chromosomal abnormalities in those cells. Such a system is expected to
include reagents to identify fetal cells, the Company's currently developed FISH
probe products (for chromosomes 13, 18, 21, X and Y) and a rapid imaging system.

Several other companies are also developing approaches to fetal cell
detection and identification. However, the Company believes that chromosomal
abnormalities in fetal cells derived from maternal blood specimens will be more
effectively analyzed with FISH probes. Based upon its patented technology, the
Company expects to participate in this market either through strategic
partnering with other companies who will use the Company's FISH probes to
complete the genetic analysis, or through the introduction of its own fetal cell
detection and identification system.

RESEARCH PRODUCTS

Vysis currently markets over 240 research use only ("RUO") DNA probes and
related reagent products. The Company's principal customers are genetics testing
laboratories and research centers

40
<PAGE>

around the world. The Company introduced 41 new RUO products in 1997. The
research reagent product line represented approximately $600,000 of the
Company's $5.4 million of product revenues in 1994, approximately $1.5 million
of the Company's $6.3 million of product revenue in 1995, and approximately $2.8
million of the Company's $11.0 million product revenue in 1996. In addition to
providing the Company with significant revenues, research reagent products
provide the Company with the ability to participate in clinical research
programs to establish correlations of various genes and genetic markers to
disease occurrence and outcome. Once correlations to disease have been
established, the Company believes that certain of its RUO products may become
candidates for high volume clinical use. Because RUO products are not used for
routine clinical diagnosis, these products are not subject to regulatory review.
Although not required to do so, the Company manufactures all of these RUO
products according to the FDA's QSR guidelines. See "Business--Government
Regulation."

The Company's research product commercialization process involves three
distinct stages prior to marketing which include, in order, research,
development and trials.

RESEARCH PRODUCTS

<TABLE>
<CAPTION>
PRODUCT TECHNOLOGY PLATFORM DISEASE/PROCEDURE POSSIBLE UTILITY STAGE
- ----------------- --------------------- ----------------- ----------------- ------------

<S> <C> <C> <C> <C>
WCP-Registered Trademark- FISH system Prenatal, Analysis of MARKETING
Probes (103 postnatal and metaphase
products) cancer chromosomes,
additions,
deletions and
translocations

CEP-Registered Trademark- FISH System Prenatal, Determination of MARKETING
Probes (45 postnatal and chromosome copy
products) cancer number

LSI-Registered Trademark- FISH System Prenatal, Determination of MARKETING
Probes (41 postnatal and gene copy number,
products) cancer chromosomal
translocations,
and presence of
microdeletions

CGH Probes and FISH System Prenatal, Determination of MARKETING
solutions (10 postnatal and chromosome region
products) cancer of amplification
and deletion
</TABLE>

41
<PAGE>
RESEARCH PRODUCTS (CONTINUED)

<TABLE>
<CAPTION>
PRODUCT TECHNOLOGY PLATFORM DISEASE/PROCEDURE POSSIBLE UTILITY STAGE
- ----------------- --------------------- ----------------- ----------------- ------------

<S> <C> <C> <C> <C>
MultiVysion-TM- FISH System Preimplantation Improved success MARKETING
PGT genetic testing rate of IN VITRO
fertilization
implantation and
successful birth

Telomere Probes FISH System Mental Detects hidden DEVELOPMENT
(42 products retardation chromosomal
planned) analysis deletions and/or
translocations
not possible with
traditional
karyotyping

Spectral FISH System Cancer and Detects hidden DEVELOPMENT
Karyotyping prenatal chromosomal
Reagent karyotyping rearrangements
analysis in 24 not possible with
colors traditional
karyotyping

Ampli-Onc-TM- gCGH Array System All cancers Detects RESEARCH
Chip substantially all
genes amplified
in cancer

Onc-Express-TM- gCGH Array System All cancers Detects genes RESEARCH
Chip expressed in
cancer
</TABLE>

The Company markets three FISH probe product lines, respectively marketed as
WCP-Registered Trademark-, CEP-Registered Trademark- and
LSI-Registered Trademark- probes and various reagents. These products are used
in a wide range of genetic research.

WCP WHOLE CHROMOSOME PAINT FISH PROBES. WCP probes fluorescently label or
"paint" the unique sequences of an entire chromosome allowing analysis of the
chromosome number as well as indicating chromosome additions and simple and
complex translocations in human metaphase cells.

CEP CHROMOSOME ENUMERATION FISH PROBES. CEP probes hybridize to repeat
sequence targets on specific chromosomes. This allows for rapid counting of
chromosomes to determine if there are too few or too many chromosomes within
interphase or metaphase cells.

LSI LOCUS SPECIFIC IDENTIFIER FISH PROBES. LSI probes hybridize to specific
locations on individual chromosomes and identify specific sequences of DNA,
which are typically gene or disease specific. By highlighting specific regions
of the chromosome, these probes quickly identify if specific genes are present
as expected or whether certain gross chromosomal changes exist.

COMPARATIVE GENOMIC HYBRIDIZATION (CGH) REAGENTS. CGH reagents are a line
of products for performing comparative genomic hybridization, a tool for
determining previously unidentified gene amplifications and deletions in genetic
diseases and cancers.

PREIMPLANTATION GENETIC TESTING ("PGT"). It is estimated that each year
some two million couples in the United States are treated for infertility
resulting in approximately 59,000 IN VITRO fertilization ("IVF") cycles. It is
not unusual for patients to undergo two or three cycles before they successfully
conceive. The direct cost for a single fertilization cycle is approximately
$7,800. Overall, approximately $2 billion is spent in the United States annually
on infertility treatments. An important contributing factor for a failed

42
<PAGE>
attempt at IN VITRO fertilization is the presence of a chromosomal abnormality
in the implanted embryo. Therefore, the IVF success rate may be improved by
using embryos that do not have chromosomal abnormalities. With only a single
cell available for this analysis, it is necessary to use a chromosomal
assessment technology capable of detecting a large number of abnormalities in a
single cell. FISH is currently the only diagnostic technology known to the
Company that has this capability.

The Company's first PGT product, based on the FISH System, is MultiVysion
PGT, which simultaneously detects abnormalities of chromosomes 13, 18, 21, X and
Y in a single cell within 4 hours. The Company believes that completing a PGT
analysis using Vysis' patented multi-color probes will increase the probability
of a successful implantation and birth at a substantially lower cost for
patients undergoing this procedure.

TELOMERE PROBES. Telomeres are unique sequences of DNA at the end of
chromosomes that contain a large number of genes. Telomeres play an integral
role in chromosome biology, structure, and function. Changes in telomeres, such
as deletions or translocations frequently missed by traditional karyotyping,
have been implicated as causes of mental retardation and cancer. There are
approximately 60,000 peripheral blood lymphocyte specimens tested each year to
evaluate patients for chromosomal causes of mental retardation. The Company is
developing a line of individual locus specific FISH probes and a multi-color
telomere panel for research in chromosomal causes of mental retardation and
cancer.

SPECTRAL KARYOTYPING REAGENT. Traditional karyotypes employ black and white
images of chromosomes and interpretation of these karyotypes requires
sophisticated training in recognition of chromosome patterns and changes in the
chromosomes. Frequently subtle translocations are missed utilizing traditional
black and white karyotyping. The Company's Spectral Karyotyping Reagent is
intended to simplify and improve the accuracy of karyotyping by providing a
unique color to each chromosome, thus allowing the detection of chromosomal
rearrangements not possible with traditional karyotyping. The Company is
developing a spectral karyotyping system comprised of a 24 color probe reagent
set and a genetic workstation that incorporates proprietary software for image
analysis of the multi-color karyotype provided by the reagent.

AMPLI-ONC AND ONC-EXPRESS CHIPS. The Company is developing an Ampli-Onc
Chip based on its gCGH Array System that will detect substantially all currently
known genes amplified in cancer. This ready-to-use array of DNA probes on a
miniaturized chip is intended to enable simultaneous assessment of a large
number of genes in patient specimens for abnormalities in specific gene counts.
The Company is also developing Onc-Express Chip, an array of DNA probes for the
simultaneous assessment of a large number of expressed genes in patient
specimens. The Company believes that simultaneous testing for multiple genetic
abnormalities is likely to accelerate research and provide clinical correlations
between chromosomal abnormalities and disease. Both of these products may enable
researchers to discover new correlations that may yield genomic products for
improved diagnosis, prognosis and predictive outcome.

INSTRUMENT PRODUCTS

Vysis currently markets a line of instrument products which includes genetic
imaging workstations and other processing instruments. Because instrument
products are developed for use in connection with both clinical and research
products, the commercialization process for instrument products mirrors the
previously described commercialization process for clinical or research reagent
products. See "--Products: Clinical Diagnostic Products" and "--Products:
Research Products." These workstations provide an integrated solution to enhance
and automate the visualization, analysis, and storage of FISH, mFISH
(simultaneous imaging of multiple FISH probes), CGH, and karyotype images. These
workstations integrate proprietary software, and readily available hardware,
such as high-resolution cameras, microscopes and desktop computer systems. The
Company's principal customers for these workstations are genetic testing
laboratories and research centers around the world. The Company has an installed
base of over 320 proprietary genetic workstations at 224 laboratories in 18
countries. The Company introduced three new instrument products in 1997. The
instrument product line represented approximately $2.2 million of the Company's
$5.4 million of product revenue in 1994, approximately $2.2 million of the

43
<PAGE>
Company's $6.3 million of product revenues in 1995, and approximately $4.3
million of the Company's $11.0 million of product revenues in 1996.

INSTRUMENT PRODUCTS

<TABLE>
<CAPTION>
PRODUCT TECHNOLOGY PLATFORM DISEASE/PROCEDURE UTILITY STAGE
- ------------------- ----------------------- ------------------- ------------------- -------------
<S> <C> <C> <C> <C>
Karyotyping Image Analysis Software Cancer and prenatal Clinical and MARKETING
Software testing research automated (FDA 510(k)
classification of cleared
chromosomes February
1990)
FISH Software FISH System Cancer and prenatal Clinical and MARKETING
testing research imaging of
FISH probes
CGH Software FISH System All cancers Research for MARKETING
chromosomal
amplifications and
deletions
Lab Manager-TM- Database Software Cancer and prenatal Patient data MARKETING
Software testing management
incorporated in
karyotyping, CGH
and FISH software
HYBrite-TM- System FISH System Cancer and prenatal Clinical and MARKETING
testing research semi-
automated
hybridization of
FISH probes
Quips mFISH FISH System Cancer and prenatal Clinical and MARKETING
Software testing research
simultaneous
imaging of multiple
FISH probes
Spectral FISH System Cancer and prenatal Clinical and DEVELOPMENT
Karyotyping testing research automated
Software classification and
imaging of
chromosomes in
24-colors
Automated Specimen FISH System, gCGH Cancer, prenatal Automates steps of RESEARCH
Processor and Test Arrays System, and viral testing FISH, gCGH Array
Instrument Molecular Lawn System and Molecular Lawn
assays
gCGH Array Reader gCGH Array System Cancer and prenatal Reads gCGH Arrays RESEARCH
testing
Molecular Lawn Molecular Lawn System Cancer, prenatal Reads Molecular RESEARCH
Reader and viral testing Lawn tests
</TABLE>

QUIPS-TM- GENETIC WORKSTATIONS AND IMAGING SOFTWARE. Genetic workstations
consist of computer hardware, imaging cameras, microscopes purchased from third
party vendors and proprietary software designed to capture, analyze, document
and store data required for cytogenetic analyses. The genetic workstation
product line includes various combinations of hardware and software for
karyotyping, FISH, mFISH (multi-target FISH) and CGH.

44
<PAGE>
HYBRITE-TM-. HYBrite is a semi-automated instrument for denaturation and
hybridization of FISH probes. The HYBrite system eliminates the need for
denaturation reagents and other temperature devices. The HYBrite shortens assay
time, eliminates steps and reduces user variability.

FOOD TESTING PRODUCTS

The Company develops, manufactures and commercializes products for the
detection and identification of food-borne pathogens to food processors and
quality control laboratories. These products, marketed under the
Gene-Trak-Registered Trademark- name, include both DNA probe products and
antibody kits for the detection of organisms found to contaminate food such as
Salmonella, E. coli, Listeria and Listeria monocytogenes. The Company's food
testing product sales were approximately $2.5 million in 1994, 1995 and 1996,
respectively.

SALES AND MARKETING

MARKETS AND CUSTOMERS

There are approximately 350 cytogenetics laboratories in the United States
that include hospital-based laboratories and non-hospital-based reference
laboratories. In addition, there are approximately 5,200 hospital-based
pathology laboratories and approximately 200 cancer research laboratories in the
United States. The combination of these laboratories creates more than 5,750
potential customers for the Company's products in the United States alone. The
Company estimates the international market for its products to be approximately
two times the size of the United States market.

MARKETING STRATEGY

The Company currently markets its products to cytogenetic laboratories,
hospitals, reference laboratories, academic and commercial research institutions
and managed care organizations. Vysis expects that the principal customers for
its clinical diagnostic products will include cytogeneticists, pathologists,
oncologists and other physicians. In order to accelerate clinical market
acceptance of its Genomic Disease Management products, the Company is developing
programs designed to (i) increase the level of awareness of FISH System products
among the clinical laboratories and the physicians who are expected to order
these tests, (ii) educate the medical community regarding the benefits of
managing disease with genomic testing products, and (iii) provide data
demonstrating clinical correlation of the disease target to disease outcome,
progression and predisposition. The Company will pursue these programs through
the use of collaborations with external laboratories and scientists who are
influential opinion leaders, the use of third-party published articles and the
publication of data obtained in product clinical trials.

SALES STRATEGY

Sales in the United States are conducted by a direct sales force, currently
consisting of a national sales manager and eight technical sales
representatives. Four representatives are dedicated to clinical and research
reagent sales. The remaining four representatives are dedicated to sales of
genetic workstations.

European sales are managed by country specific managers supported by a nine
person direct sales organization for Germany, France and the United Kingdom.
This organization is further supported by independent distributors in Austria,
Czech Republic, Egypt, Finland, Greece, Holland/Belgium, Hungary, India, Israel,
Italy, Poland, Saudi Arabia, Spain, Sweden, Switzerland, Turkey and the United
Arab Emirates.

Sales and marketing in Japan is conducted through a marketing partnership
with Fujisawa Pharmaceutical Co., Ltd. ("Fujisawa"). The partnership, entered
into in July 1995, provides Fujisawa with a ten-year exclusive distribution
right to market Vysis FISH probes and genetic workstations in Japan. Fujisawa is
responsible for funding all clinical regulatory compliance for the Japanese
market. Vysis will supply all of its United States and European clinical trial
data for its FISH products to assist Fujisawa in its regulatory approval
efforts. The agreement provides that Fujisawa will pay the Company $600,000 per
year through July 1999. Fujisawa introduced the Company's clinical research
reagent product line in December 1995 and released the Company's genetic
workstations in 1996.

45
<PAGE>
Sales in the other world markets are conducted through the use of local
distributors. To date, additional Far East distribution channels have been
established in Australia, China, Korea, Philippines, Singapore, Taiwan and
Thailand. Other distributors have also been established for Canada and
Argentina. These distributors are supported through the Company's United States
headquarters. See Note 9 of Notes to Consolidated Financial Statements for
financial information of the Company organized by geographic area.

MANUFACTURING

The Company's manufacturing operations encompass the production and
packaging of DNA probes and reagents, as well as the integration of the
Company's imaging software with off-the-shelf electronic cameras, computer
systems and other computer peripheral equipment. The Company's manufacturing
operations utilize a complete material requirements planning system fully
integrated with the Company's finance department for operational control. The
Company believes that current manufacturing processes are readily scaleable to
meet expected growth.

The reagent and instrument manufacturing processes are performed according
to the FDA's Quality System Regulation ("QSR"), which replaced the FDA's Good
Manufacturing Practices ("GMP") criteria. The Company trains employees for
compliance with current QSR requirements as specified by the FDA. See
"Business--Government Regulation." The Company is ISO 9001 certified. ISO 9001
is the most comprehensive of all the International Organization for
Standardization quality standards and is an important element of the Company's
strategy to commercialize its products globally.

COLLABORATIONS

The Company has established a series of collaborations designed to
accelerate gene discovery efforts and correlation studies to link genetic
abnormalities to disease outcomes, from which it will obtain diagnostic and
therapeutic rights. The Company also monitors on-going worldwide medical
research in this area, such as the Human Genome Project. It is anticipated that
the Human Genome Project will complete the sequencing of the entire human genome
by 2005, which the Company believes will give rise to additional clinical
product leads. In addition, the Company has collaborations for the further
development of its technology platforms.

UNIVERSITY OF CALIFORNIA, SAN FRANCISCO

The Company funds research at the Department of Laboratory Medicine,
University of California, San Francisco ("UCSF") Cancer Center at the UCSF
Medical School, directed by Dr. Joseph Gray, in the field of molecular
cytometry. This research examines correlations of chromosome abnormalities to
disease and discovery of genes related to regions of abnormalities identified by
CGH. This research has resulted in CGH studies of samples of all major solid
tumor cancers to identify common regions of chromosome abnormality. These
studies will be used as leads for gene discovery efforts. This work has resulted
in the discovery of gene sequences in the chromosome region 20q13.2 related to
an aggressive form of breast cancer. The Company has an exclusive license to
patent rights covering inventions made from this research which relate to FISH
or CGH. The Company has an option to obtain an exclusive license for both
diagnostic and therapeutic use to patent rights covering gCGH and any gene
discoveries made from this research. The research collaboration with UCSF also
involves work on imaging software with the Company holding an exclusive license
to any software improvements.

THE MAYO CLINIC

The Company funds research by Dr. Robert Jenkins at the Mayo Clinic's
Department of Cytology in the area of correlation of chromosomal abnormalities
to aggressive forms of prostate cancer and genes associated with metastatic
potential. As part of the collaboration, Dr. Jenkins has developed correlations
of chromosomal aneuploidies to prostate cancers. These correlations are under
investigation as potential targets for clinical products relating to prostate
cancer. The Company has an option to obtain an exclusive license to any
correlations discovered during this collaboration.

46
<PAGE>
DIGITAL SCIENTIFIC

In January 1996, the Company and Digital Scientific Ltd. ("Digital") entered
into an exclusive marketing and software co-development agreement to market
Digital's SmartCapture-TM- FISH imaging software under which the Company also
acquired a worldwide exclusive license to market all of Digital's imaging
software products. In addition, the Company and Digital agreed to co-develop
imaging software to be marketed by the Company as part of its Quips Genetic
Workstations. The Company and Digital will co-own the software products
developed under the agreement. The Company has an option to acquire an exclusive
license from Digital on certain of these co-owned products.

PUBLIC HEALTH RESEARCH INSTITUTE OF NEW YORK

The Company funds a research and development collaboration and supports
broad based QBR research activities in the laboratory of Dr. Fred Kramer at the
Public Health Research Institute ("PHRI") of New York in New York City. Dr.
Kramer is one of the principal inventors of QBR amplification technology and has
been actively involved in QBR research since 1985. The Company has an exclusive
license to pending United States and foreign patent applications claiming
QBR-based binary probe ligation assay, as well as to any inventions made at PHRI
in this collaboration.

INCYTE PHARMACEUTICALS

In July 1996, the Company entered into a collaboration with Incyte
Pharmaceuticals, Inc. ("Incyte"), a leading genomic database company, and with
Genome Systems, Inc., a subsidiary of Incyte providing positional cloning and
library screening services, to produce a "bottoms-up" genomic map which will map
expressed human gene sequences to their human chromosome locations. The Company
expects that use of the map and its associated BAC library will reduce the time
to generate a BAC based "contig" by one to two years. As part of the
collaboration, the Company will have access to Incyte's LifeSeq-TM- database for
sequence data on expressed human gene sequences, use of the developed genomic
map and the associated BAC contigs.

The Company believes that the BAC contigs will be used to develop additional
FISH RUO probes and may provide a source of targets to be placed on the gCGH
Arrays. The Company believes that access to the LifeSeq database and the map
will accelerate the discovery of genes located in regions of chromosomes
identified as important in cancer by CGH technology.

PRODUCT LEAD COLLABORATIONS

The Company has also established additional research collaborations aimed at
generating clinical product opportunities, although there can be no assurances
of successful development of clinical reagent products based upon any of these
research efforts. A collaboration with the University of Chicago is aimed at
producing a set of telomere probes for each human chromosome and establishing
clinical use of these probes for the diagnosis of mental retardation. The
Company is developing a RUO FISH probe for detection of a chromosomal
translocation in pediatric leukemia under an exclusive license from St. Jude
Children's Research Hospital. The Company's collaboration with the Reproductive
Genetics Institute is directed at establishing the utility of the Company's FISH
probes in pre-implantation genetic testing.

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY GRANTS

The Company has been awarded two United States Department of Commerce grants
totaling $4 million for research related to the Company's technologies. These
grants are administered through the Advanced Technology Program ("ATP") of the
National Institute of Standards and Technology ("NIST") within the United States
Department of Commerce. The first grant, for research related to the gCGH
technology platform, was initiated in March 1995 and runs through March 1998.
The second grant, for research related to the development of the Company's
Molecular Lawn technology platform and other research, was initiated in August
1995 and will run through August 1998.

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<PAGE>
PATENTS AND LICENSE RIGHTS AND PROPRIETARY INFORMATION

The Company currently holds or has exclusive licenses to 92 issued United
States patents or allowed United States patent applications, to 69 pending
United States patent applications, and to additional foreign patents and pending
patent applications in various areas of genetic and infectious disease testing.
The exclusive licenses held by the Company relating to these patents and patent
applications also grant the Company the exclusive right to grant sublicenses.
The Company believes that its patent portfolio covering FISH, CGH, gCGH and QBR
contains several patents of commercial significance to its activities in the
clinical market. The Company also believes that its FISH, CGH and gCGH patent
portfolio will provide opportunities to obtain an exclusive position in the
clinical market on certain general assay formats as well as particular targets
and to seek licenses and cross-licenses. The Company further believes that, in
the absence of any licensing or cross-licensing to third parties by the Company,
its QBR patent portfolio will provide an exclusive opportunity to use QBR
amplification methods. The following describes significant patent assets of the
Company.

FISH TECHNOLOGY

U.S. Patent 5,447,841, issued September 5, 1995, licensed exclusively from
the University of California covers methods of IN SITU hybridization using
unique sequence probes and unlabeled blocking DNA. These methods permit the use
as DNA probes of DNA sequences which are produced by standard cloning procedures
without removal of any repeat DNA sequences which are present. The Company
believes that the alternative manufacturing technologies to produce labeled FISH
probes which do not contain the repeat DNA sequences are difficult to implement
and are not proven commercially. The Company is also licensed exclusively under
three pending United States divisional patent applications stemming from the
'841 patent. Each of these applications claims priority of the '841 patent
applications filed on January 16, 1986 and December 1, 1986. The divisional
applications cover other embodiments of IN SITU hybridization using unique
sequence probes, including detection of abnormalities on chromosome 21 and
detection of gene amplification or gene deletion.

DIRECT LABELING TECHNOLOGY

U.S. Patent 5,491,224, issued February 13, 1996, and its pending foreign
counterpart applications, claim the Company's direct label FISH DNA probes and
their manufacture. U.S. Patent 5,663,319, issued September 2, 1997 covers
multiple direct label FISH probe compositions. The Company has received a
counterpart European patent on its direct label FISH DNA probes and on methods
of IN SITU hybridization using multiple direct label FISH DNA probes. The
Company has a pending United States divisional patent application of the '224
patent claiming use of direct label FISH DNA probes.

CGH AND GCGH TECHNOLOGY

The Company is exclusively licensed by the University of California under
U.S. Patent 5,665,549, issued September 9, 1997, and other pending United States
and foreign patent applications claiming basic CGH methods to detect changes in
copy number of DNA sequences at a particular chromosome location. The Company
also holds an option from the University of California to obtain an exclusive
license to pending U.S. and foreign patent applications claiming gCGH assays.

Q-BETA REPLICASE TECHNOLOGY

The Company holds exclusive licenses from Columbia University/Salk Institute
and from PHRI on United States and foreign patents and pending patent
applications relating to the use of QBR as an amplification technology to detect
nucleic acid targets. These include U.S. Patent 4,786,600 issued November 22,
1988, claiming "substrate" molecules having inserted probe sequences which are
replicatable by QBR and U.S. Patent 4,957,858, issued September 18, 1990,
claiming nucleic acid detection assays

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using QBR. The Company also has a number of United States and foreign patents
and pending patent applications covering QBR and the Molecular Lawn technology.

CORRELATIONS OF CHROMOSOMAL ABNORMALITIES TO DISEASE

The Company is pursuing a strategy to acquire rights to methods correlating
particular genetic aberrations to disease. These rights will potentially provide
opportunities for exclusive positions on clinical assays. For example, U.S.
Patent 5,472,842 and its pending foreign counterpart applications, licensed
exclusively from the University of California, cover methods of detection of a
chromosomal abnormality on chromosome 20 at locus 20q13 which has been
correlated to certain forms of breast cancer. The Company holds an option from
the University of California for an exclusive license for therapeutic and
diagnostic uses to United States and foreign patent applications claiming gene
sequences in the chromosome 20q13 locus. The Company is also exclusively
licensed under United States and foreign patent applications from the University
of California, St. Jude Children's Research Hospital and Canji, Inc. claiming
methods to diagnose disease based upon correlations of particular chromosomal
abnormalities for colon cancer, breast cancer, lung cancer, bladder cancer,
ovarian cancer, prostate cancer, gliomas and leukemias.

ABILITY TO PRACTICE TECHNOLOGY

The Company's success will depend to a substantial degree upon its ability
to operate its business and to develop, manufacture, market and sell its
products without infringing the proprietary rights of third parties. However,
numerous United States and foreign issued patents and pending patent
applications, which are owned by third parties, exist in the general fields of
nucleic acid technology and clinical diagnostic technology. A partial list of
more specific technologies in these general fields includes patents and patent
applications relevant to nucleic acid probe manufacturing, labels for nucleic
acid probes, nucleic acid probe compositions, nucleic acid probe hybridization
assays, nucleic acid amplification methods, full length gene sequences, full
length expressed gene sequences, partial gene and expressed gene sequences, gene
expression assays, correlations of chromosome or gene abnormalities to disease,
gene point mutation detection assays, oligonucleotide array hybridization
methods, patient sample processing, fetal cell identification and separation,
imaging apparatus and methods, infectious disease detection assays, food testing
assays and apparatus related to these technologies. The Company expects that
additional United States and foreign patents owned by third parties will issue
and additional United States and foreign patent applications owned by third
parties will be filed in these fields. The Company further believes that the
level of patent competition in these fields is sufficiently high that patent
litigation in these fields is likely to occur.

Consequently, the Company believes that its management of the business risks
presented by the intense patent competition in these fields is critical to its
ability to operate its business and to develop, manufacture, market and sell its
products. There can be no assurance that the Company will be able to
successfully manage these patent business risks to avoid infringing the
proprietary rights of others nor can there be any assurance that patent
infringent suits will not be brought against the Company. Any failure in its
management of these patent business risks may have a material adverse impact on
the Company's business, financial condition and results of operations.

The Company's success will also depend to a substantial degree upon its
ability to obtain and maintain patent protection, both in the United States and
in foreign countries, for its products and methods and other inventions, which
the Company believes patentable, as well as upon the Company's ability to
preserve its trade secrets and to protect its software copyrights. The Company's
success will also depend to a substantial degree upon its collaborators' and
future licensors' ability to obtain and maintain patent protection, both in the
United States and in foreign countries, on gene discoveries, the correlations of
disease to genomic abnormalities and other inventions relevant to the Company's
business, as well as upon the Company's collaborators' and future licensors'
ability to preserve trade secrets and to protect their software copyrights.

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The patent position of a company utilizing biotechnology generally is highly
uncertain and involves complex legal and factual questions. There can be no
assurance that any patents owned by or licensed to the Company will not be
challenged and subsequently invalidated or circumvented, or that such patents
will be sufficiently broad to afford protection against third parties who
develop or use similar technology, or that any of such patents will be
successfully asserted against any infringing activity, or that any of the
Company's patent rights will be successfully cross-licensed to third parties in
exchange for a license under their patent rights. In addition, there can be no
assurance that any pending United States or foreign patent applications owned or
licensed by the Company or those acquired or licensed by the Company in the
future will result in issued patents, or that such applications will not be
subject to foreign opposition seeking the revocation of a Company patent or to
United States patent interference seeking a determination that the Company or
its collaborators were not the first inventor of a particular patent or patent
application, or that the Company or its collaborators will develop additional
technologies that are patentable, or that any patents owned or licensed to the
Company will provide a basis for commercially viable products or services.

The Company is also aware of issued United States and foreign patents and
pending patent applications owned or controlled by third parties, which are
related to the Company's current or anticipated technologies. Specifically, the
Company is aware of issued United States and foreign patents and pending patent
applications owned or controlled by third parties, which are related to
significant elements of the Company's FISH, CGH and direct labeling
technologies, or to significant elements of the Company anticipated use of its
QBR technologies, or to reagents useful in the performance of CGH or gCGH
assays. Although the Company believes that certain of these issued patents are
not infringed by the Company's current and planned operations, there can be no
assurance that the Company would be able to successfully assert such a position
in the courts, nor that such a position could be asserted without the Company
incurring substantial or prohibitive costs. Furthermore, because United States
patent applications are maintained under conditions of confidentiality while the
applications are pending in the United States Patent and Trademark Office, there
may be pending patent applications filed by third parties of which the Company
is unaware and which relate to the Company's current or planned technologies. In
addition, third parties may in the future file patent applications having claims
that relate to the Company's services, processes or products. Persons holding or
licensing patent rights could bring legal actions against the Company claiming
that any of the Company's marketing, services, processes or products, or the
Company's collaborators' or its suppliers' services or products or of the
Company's customers' use of the Company's services or products infringe one or
more of their patents, and seek damages or injunctive relief. Patent litigation
is costly, and there can be no assurance that the Company would prevail in any
patent litigation brought against it. Further, the Company could be subject to
significant liabilities to such persons, may be required to obtain licenses from
such persons, or may be required to cease certain activities, and any of these
could have a material adverse effect upon the Company's business, financial
condition or results of operations. In addition, there can be no assurance that
the Company will be able to obtain such licenses on commercially reasonable
terms, or at all.

The Company is party to various license and license option agreements
(including but not limited to agreements with the University of California, Ciba
Corning Diagnostics, PHRI, Columbia University and the Salk Institute), which
give the Company rights to use certain technologies fundamental to the Company's
business. Although the Company believes it is currently in compliance with all
performance criteria contained in such license and option agreements, failure of
the Company to meet such criteria in the future could cause the loss of such
licenses or options, or a change in license status from exclusive to
nonexclusive. Furthermore, any contractual relationship with a third party may
involve complications and the potential for disputes. Licensors of the Company
may disagree with the Company as to the interpretation of the terms and
conditions of the Company's licenses, as to whether the Company or licensor have
properly fulfilled the provisions of such license contracts, and may challenge
the Company's activities under such licenses in the courts or in arbitration
proceedings. Any of the foregoing could have a material adverse effect on the
Company's business, financial condition and results of operations.

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Certain of the Company's licensed patent rights claim inventions, which were
developed in whole or in part using grants or funding from United States
Government agencies, such as the National Institutes of Health and the
Department of Energy. The Company is also developing technology funded in part
by two ATP grants from the NIST. The Company expects that patentable inventions
and patent rights covering such inventions could result from the activities
funded by these two ATP grants. The terms of the United States Government's
funding of the Company's licensors and of the Company provide that the United
States Government is provided certain rights to use the technology developed by
the grants or funding and to practice or license under the applicable patent
rights for the United States Government's benefit. The applicable United States
statute governing the United States government's rights (the "Dole-Bayh Act")
also provides that third parties may petition the government for a grant of a
non-exclusive license upon reasonable terms under these patent rights owned or
exclusively licensed to the Company if the Company is found to not be diligently
developing the technology or market covered by the patent(s) in question. There
can be no assurance that the United States Government will not exercise such
rights, or that the exercise of such rights would not have a material adverse
effect on the Company.

The Company also relies upon copyrights, copyright licenses and trade
secrets to protect all of its software and upon trade secrets to protect certain
of its unpatented proprietary technology. There can be no assurance that the
Company will be able to adequately protect its rights in such software and such
unpatented proprietary technology or that others will not independently develop
substantially equivalent technology or information, or that others will not
otherwise gain access to the Company's software and unpatented proprietary
technology or disclose the Company's software and unpatented proprietary
technology to third parties in a non-confidential manner.

The Company's development of its imaging software products is subject to all
of the risks of the software development industry. There can be no assurance
that the Company's software development will not be adversely impacted or
delayed due to changes in its suppliers' products or software, unforeseen
programming needs, delay or failure to receive software development services
from third parties, or the Company's inability to obtain necessary computer
products, software and components on a timely basis. Any inability of the
Company to develop its imaging software products or its disease modeling
software on a timely basis may have a material adverse impact on the Company.

The Company does not presently attempt to obtain patent rights covering its
software developments. However, third parties may have pending patent
applications or obtain patents covering imaging software or disease modeling
software technologies. There can be no assurance that the Company would not be
forced to begin additional patenting efforts in the imaging software and disease
modeling software fields, nor that the Company's attempts to obtain such patents
on its software developments would be successful, nor that the Company would not
be adversely affected by third parties obtaining patents on such software.

Any of the risks and uncertainties concerning the ability to practice
technology which are described herein apply to the Company's collaborators just
as they apply to the Company itself. As a licensee or strategic partner of such
collaborators, the Company could be materially adversely affected by any event
adversely affecting one or more of the Company's collaborators.

COMPETITION

Competition in clinical diagnostics and genomics is intense and is expected
to increase as the market for Genomic Disease Management products develops.
Competition is and will continue to be based on quality, reliability, accuracy,
ease of use, price and product line offering. Oncor, Inc. ("Oncor") is a major
competitor in the supply of FISH products to the research market and is seeking
to enter the clinical market with FISH products. Applied Imaging Corp. and
Perceptive Scientific Instruments, Inc. compete with Vysis in the marketing of
genetic imaging workstations. The Company is aware of other entities that
currently market RUO nucleic acid products, which may have the ability to
compete with the Company in

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the clinical market. In addition, many reference laboratories and research
institutions produce their own FISH probes for internal use.

Other companies are developing genomic assessment products including "DNA
Chip" products for assessment of gene expression or gene sequence with potential
use for clinical diagnostics. Other diagnostic companies may enter the genetic
disease diagnostic market with nucleic acid based technologies. Many of the
Company's existing and potential competitors have substantially greater
financial, marketing, sales, distribution and technological resources than the
Company or may have substantial advantages over the Company in terms of research
and development expertise, experience in conducting clinical trials, experience
in regulatory matters, manufacturing efficiency, name recognition, ability to
obtain necessary intellectual property licenses, sales and marketing expertise
and distribution channels. There can be no assurance that the Company will be
able to compete successfully against current or future competitors.

LITIGATION

The Regents of the University of California (the "Regents") and the Company
as exclusive licensee, are plaintiffs in a patent infringement suit filed
September 5, 1995, against Oncor. The suit was filed in the United States
District Court in San Francisco, California and asserts that Oncor's marketing
of various DNA probe products infringes the Regents' U.S. Patent No. 5,447,841.
The Company and the Regents share equally the legal costs of this suit. Oncor's
answer to the complaint asserts that the patent is invalid based on prior art
and the failure to disclose the best mode of practicing the invention and that
it is unenforceable due to inequitable conduct which occurred during prosecution
of the patent. On August 19, 1997, the court issued an order which (i) granted
the Regents' and Vysis' motion for claim construction and denied Oncor's
competing motion for claim construction, (ii) granted the Regents' and Vysis'
motion for summary judgment that the claims were novel and denied Oncor's motion
for summary judgment that the claims were invalid as anticipated, (iii) granted
the Regents' and Vysis' motion for summary judgment that the claims were
unobvious and denied Oncor's motion for summary judgment that the claims were
invalid as obvious, (iv) granted in part and denied in part the Regents' and
Vysis' motion for summary judgment that Oncor's use and marketing of its
challenged FISH probes infringed the claims and denied Oncor's motion for
summary judgment that none of its FISH probes infringed, (v) granted in part and
denied in part the Regents' and Vysis' motion for summary judgment regarding the
best mode of practicing the invention, (vi) denied Oncor's motion for summary
judgment that the claims were unenforceable because of material
misrepresentations made to the U.S. Patent & Trademark Office by the Regents
during prosecution of the patent, and (vii) struck Oncor's motion for summary
judgment that the claims were unenforceable because the Regents failed to submit
material prior art to the U.S. Patent & Trademark Office. The trial of the
remaining issues is scheduled to begin in April 1998. If Oncor were to succeed
in invalidating the patent or having it declared unenforceable, this may have a
material adverse effect on the Company's market position and future business
prospects.

The Company and Amoco are defendants in a suit pending in the United States
District Court in San Diego, California brought by Gen-Probe, Inc. ("Gen-Probe")
in June 1995. The suit alleges infringement of U.S. Patent Nos. 4,851,330 and
5,288,611 (the "Kohne Patents"). The Kohne Patents are alleged to apply
generally to the detection, identification and quantification of non-viral
organisms using DNA probes selected to target sequences of ribosomal RNA. The
allegedly infringing activities are the manufacture, use and sale of reagents
and kits for detecting certain food and environmental pathogens currently used
in the Company's food testing business. The suit also alleges various claims
that the Company competed unfairly with Gen-Probe. This suit has been stayed
pending the outcome of a separate suit brought in California Superior Court in
San Diego, California against Gen-Probe by the Center for Neurologic Study
("CNS") challenging Gen-Probe's claim to sole ownership of the Kohne Patents.
CNS asserts that the invention of the Kohne Patents were made by David Kohne
while he was affiliated with CNS and supported by a grant from the National
Institutes of Health naming CNS as the grantee

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institution. CNS seeks damages and title in the Kohne Patents. Pursuant to
separate agreements between Amoco and CNS, which has been assigned to the
Company by Amoco, the Company reimburses CNS for legal costs incurred in the
suits. In return, the Company receives contingent rights to acquire an exclusive
license with the right to grant sub-licenses under such rights as CNS may obtain
in the Kohne Patents. Further, the Company has contractually agreed with CNS to
grant sub-licenses at commercially fair and reasonable terms under the Kohne
Patents should it acquire the exclusive license. CNS' suit against Gen-Probe was
bifurcated into two phases. The first phase would be tried by a jury in December
1997 and would decide whether certain claims were barred as untimely. If the
claims were not found to be untimely, the second phase would be tried separately
in March 1998 and would decide the remaining issues raised by CNS. On December
16, 1997, upon completion of the first phase of the trial, the jury determined
that the claims before it were barred as untimely. The Company believes that CNS
is evaluating its available options including its ability to pursue its
remaining claims, whether to request a new trial and whether to appeal the
Court's rulings relating to the first phase. There can be no assurance that the
Company will obtain rights under the Kohne Patents.

Counterpart applications to the Kohne Patents were filed in Europe, Japan
and elsewhere. Patents were granted and the Company has opposed these patents in
Europe and Japan. The opposition has not been resolved in Europe. In Japan, the
Company's opposition has been rejected and the patent maintained. There can be
no assurance that Gen-Probe will not assert additional counts of infringement
based on any additional patents issued from the applications underlying the
Kohne Patents or will not assert additional causes of action against the
Company. Although the Company believes that it has meritorious defenses to the
suit by Gen-Probe against the Company, there can be no assurance that the
Company will ultimately prevail. An adverse determination could include an award
of treble damages and/or attorneys' fees, which could have a material adverse
effect on the financial condition and results of operations of the Company.
Furthermore, an adverse determination in such suit may limit future business
opportunities that the Company might otherwise be able to exploit in the area of
infectious disease detection.

Prior to the closing of this offering, the Company and Amoco will enter into
a Cooperation Agreement relating to the establishment of the Company as a
stand-alone entity. The Cooperation Agreement will provide that Amoco and the
Company will cooperate in the defense of the suit brought by Gen-Probe and will
include an allocation of any liability arising from the Gen-Probe suit or the
suit brought by CNS. Under this allocation, Amoco will agree to indemnify the
Company against any loss or damage based upon Gen-Probe's allegations of unfair
competition and related claims in the suit. The Company will agree to indemnify
Amoco against any loss or damage based upon the patent infringement count in the
suit or any other cause of action not yet asserted by Gen-Probe. Under this
indemnity the Company will also be responsible for the attorney's fees and costs
associated with the defense of the patent infringement count. There can be no
assurance that the indemnity of the Company by Amoco will prevent an adverse
determination from having a material adverse impact upon the Company.

GOVERNMENT REGULATION

Unless specifically exempted, a medical device may be marketed in the United
States only with the FDA's prior authorization. Devices classified by FDA as
posing less risk are placed either in class I or II and require the manufacturer
to seek 510(k) clearance from the FDA. Such clearance generally is granted when
submitted information establishes that a proposed device is "substantially
equivalent" in intended use and safety and effectiveness to a "predicate
device," which is either a class I or II device already legally

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on the market or a "preamendment" class III device (i.e., one that has been in
commercial distribution since before May 28, 1976) for which the FDA has not
called for PMA applications. Obtaining a 510(k) clearance usually takes from
four to twelve months or more from the date of submission. There can be no
assurance that 510(k) clearance will ever be obtained. During this process, the
FDA may determine that it needs additional information or that a proposed device
is precluded from receiving clearance because it is not substantially equivalent
to a predicate device. After a device receives clearance, any modification that
could significantly affect its safety or effectiveness, or would constitute a
major change in the intended use of the device, will require a new 510(k)
submission.

A device that does not qualify for 510(k) clearance is placed in class III,
which is reserved for devices classified by the FDA as posing the greatest risk
(E.G., life-sustaining, life-supporting or implantable devices, or devices that
are not substantially equivalent to a predicate device). A class III device
generally must obtain PMA approval, which requires the manufacturer to establish
the safety and effectiveness of the device to the FDA's satisfaction. A PMA
application must provide extensive preclinical and clinical trial data and also
information about the device and its components regarding, among other things,
manufacturing, labeling and promotion. As part of the PMA review, the FDA will
inspect the manufacturer's facilities for compliance with the Quality System
Regulation ("QSR"), which mandates elaborate testing, control, documentation and
other quality assurance procedures.

Upon submission, the FDA determines if the PMA application is sufficiently
complete to permit a substantive review, and, if so, the application is accepted
for filing. The FDA then commences an in-depth review of the PMA application,
which typically takes one to three years or more. The review time is often
significantly extended as a result of the FDA asking for more information or
clarification of information already provided. The FDA also may respond with a
"not approvable" determination based on deficiencies in the application and
require additional clinical trials that are often expensive and time consuming
and can delay approval for months or even years. During the review period, an
FDA advisory committee, typically a panel of clinicians, likely will be convened
to review the application and recommend to the FDA whether, or upon what
conditions, the device should be approved. Although the FDA is not bound by the
advisory panel decision, the panel's recommendation is important to the FDA's
overall decision making process.

If the FDA's evaluation of the PMA application is favorable, the FDA
typically issues an "approvable letter" requiring the applicant's agreement to
specific conditions (E.G., changes in labeling) or specific additional
information (E.G., submission of final labeling) in order to secure final
approval of the PMA application. Once the approvable letter is satisfied, the
FDA will issue a PMA for the approved indications, which can be more limited
than those originally sought by the manufacturer. The PMA can include
postapproval conditions that the FDA believes necessary to ensure the safety and
effectiveness of the device including, among other things, restrictions on
labeling, promotion, sale and distribution.

Failure to comply with the conditions of approval can result in material
adverse enforcement actions, including the loss or withdrawal of the approval.
The PMA process can be expensive and lengthy, and no assurance can be given that
any PMA application will ever be approved for marketing. Even after approval of
a PMA, a new PMA or PMA supplement is required in the event of a modification to
the device, its labeling or its manufacturing process.

The Company is conducting clinical trials for the FISH detection of
HER-2/neu amplification in breast cancer. The clinical trial protocols were
reviewed by the FDA for adequate design to meet the intended use and clinical
utility claims. The Company obtained verbal permission in March 1997 to conduct
these trials. Clinical trials are scheduled to be completed in early 1998 with a
PMA submission expected to be made to the FDA in the first half of 1998. There
can be no assurance, however, that the FDA's PMA Advisory Panel will agree with
the adequacy of the study design. There can be no assurance that this product
will be approved by the FDA.

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Although clinical investigations of most devices are subject to the
investigational device exemption ("IDE") requirements, clinical investigations
of IN VITRO diagnostic ("IVD") tests are exempt from the IDE requirements,
including FDA approval of investigations, provided that the testing meets
certain exemption criteria. IVD manufacturers must also establish distribution
controls to assure that IVDs distributed for the purpose of conducting research
use or clinical investigations are used only for that purpose and are not
commercialized. Pursuant to current FDA policy, manufacturers of IVDs labeled
for research use only ("RUO") or investigational use only ("IUO") are strongly
encouraged by the FDA to establish a certification program under which
investigational IVDs are distributed to or utilized only by individuals,
laboratories or health care facilities that have provided the manufacturer with
a written certification of compliance indicating that the RUO or IUO product
will be restricted in use and will, among other things, meet institutional
review board ("IRB") and informed consent requirements. The FDA recently issued
a Compliance Policy Guide setting forth, among other things, the FDA's intent to
undertake a heightened enforcement effort with respect to RUO and IUO devices
improperly commercialized prior to receipt of FDA clearance or approval.

The Company has developed tests, software and instrument systems that it
distributes in the United States on a RUO or IUO basis. Failure of the Company
or recipients of the Company's RUO and IUO devices to comply with the regulatory
limitations on the distribution and use of such devices could result in
enforcement action by the FDA that would adversely affect the Company's ability
to distribute the tests prior to obtaining FDA clearance or approval. Such
restrictions could have a material adverse effect on the Company's business,
financial condition and results of operations.

Purchasers of the Company's clinical diagnostic products in the United
States may be regulated under the Clinical Laboratory Improvement Amendments of
1988 ("CLIA") and related federal and state regulations. CLIA is intended to
ensure the quality and reliability of clinical laboratories in the United States
by mandating specific standards in the areas of personnel qualifications,
administration, participation in proficiency testing, patient test management,
quality control, quality assurance and inspections. The regulations promulgated
under CLIA established three levels of diagnostic tests ("waived", "moderately
complex" and "highly complex") and the standards applicable to a clinical
laboratory depend on the level of the tests it performs. The Company believes
that its FISH, gCGH Array and Molecular Lawn tests will be placed in the "high
complexity" category under CLIA regulations, which will likely limit their use
to larger hospitals and clinical reference laboratories. CLIA requirements may
prevent some clinical laboratories from using any or all of the Company's
diagnostic products. There can be no assurance that the CLIA regulations and
future administrative interpretations of CLIA will not have a material adverse
impact on the Company by limiting the potential market for the Company's FISH
and other products.

Some clinical laboratories prepare their own finished diagnostic tests using
purchased reagents. The FDA has generally not exercised regulatory authority
over these individual reagents or such finished tests. In November 1997, the FDA
issued new rules for these reagents, individually termed an analyte specific
reagent ("ASR"), that would apply a regulatory framework to them, including
restrictions on sales or promotional claims that could be made about these
products and the restriction of sales to clinical laboratories certified under
CLIA as high complexity testing laboratories. The Company sells on an RUO basis
a number of individual reagents that likely fall within the ASR regulatory
framework, which may therefore require changes in the Company's marketing and
labeling of such products. The Company is currently evaluating the new ASR
regulatory framework in order to assess the possible impact upon the Company's
ongoing operations and the marketing of its products as ASRs.

The Company anticipates marketing a panel of FISH probes for use in
connection with IN VITRO fertilization ("IVF") procedures for preimplantation
genetic testing ("PGT"). Current FDA policy permits the distribution of certain
IN VITRO assays on an RUO basis, provided that the assays are not commercialized
on an unrestricted basis. The Company believes that it can distribute its
MultiVysion PGT panel, as well as its Quips Genetic Workstations, to IVF centers
on an RUO basis. In addition, the Company believes that FDA policy regarding its
IVF panel and similar products may evolve over time in a manner which would

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permit such products to be commercially distributed on an unrestricted basis
with only specified labeling and QSR requirements being imposed. The FDA has to
date not developed a definitive policy in this area, and there can be no
assurance that FDA will not issue guidelines or take other regulatory actions
which might adversely impact the Company's anticipated revenues from its RUO
sales or subsequent unrestricted commercial sales of its MultiVysion PGT panel
to IVF centers.

Any devices manufactured or distributed by the Company pursuant to FDA
clearances or approvals will be subject to pervasive and continuing regulation
by the FDA and certain state agencies. The Company will be subject to routine
inspection by the FDA and will have to comply with the host of regulatory
requirements that usually apply to medical devices marketed in the United
States, including labeling regulations, the QSR, the Medical Device Reporting
regulation (which requires a manufacturer to report to the FDA certain types of
adverse events involving its products), and the FDA's prohibitions against
promoting products for unapproved or "off-label" uses. Unanticipated changes in
existing regulatory requirements or adoption of new requirements could have a
material adverse effect on the Company. The Company's failure to comply with
applicable regulatory requirements could result in enforcement action by the FDA
or foreign governments, which could have a material adverse effect on the
Company's business, financial condition and results of operations.

The President recently signed into law the Food and Drug Administration
Modernization Act of 1997. This legislation makes changes to the device
provisions of the Food, Drug and Cosmetic Act and other provisions in the Act
affecting the regulation of devices. Among other things, the changes will affect
the IDE, 510(k) and PMA processes, and also will affect device standards and
data requirements, procedures relating to humanitarian and breakthrough devices,
tracking and postmarket surveillance, accredited third party review, and the
dissemination of off-label information. The Company cannot predict how or when
these changes will be implemented or what effect the changes will have on the
regulation of the Company's products. There can be no assurance that the new
legislation will not impose additional costs or lengthen review times for the
Company's products.

Unanticipated changes in existing regulatory requirements, failure of the
Company to comply with such requirements or adoption of new requirements could
have a material adverse effect on the Company. The Company also is subject to
numerous federal, state and local laws relating to such matters as safe working
conditions, manufacturing practices, environmental protection, fire hazard
control and hazardous substance disposal. There can be no assurance the Company
will not be required to incur significant costs to comply with such laws and
regulations in the future or that such laws or regulations will not have a
material adverse effect upon the Company's business, financial condition and
results of operations.

EMPLOYEES

As of December 31, 1997, the Company had 151 full-time employees, of whom 33
hold Ph.D. degrees, one holds an M.D. degree and 26 hold other advanced degrees.
Of the Company's total work force, 43 are in research and development, 45 are in
sales/marketing, 17 are in regulatory affairs, 23 are in operations, and 23 are
in business development, legal, finance, human resources, and administration.
The Company believes that its future success will depend, in part, on its
continuing ability to attract, retain, and motivate qualified scientific,
technical, and managerial personnel. The Company faces intense competition in
this

56
<PAGE>
regard from other companies, research and academic institutions, government
entities and other organizations. None of the Company's employees is represented
by a collective bargaining agreement, nor has the Company experienced work
stoppages. The Company believes that its relations with its employees are good.

FACILITIES

The Company's executive offices, research and development activities,
manufacturing operations and administrative support are located in Downers
Grove, Illinois. This 56,551 square foot facility is leased pursuant to a lease
that expires on November 30, 2004. Capacity exists at such location to expand
production to accommodate future growth.

The Company also leases 3,300 square feet of space in Stuttgart, Germany
under a lease that expires in October 2000. The Company has leased 3,014 square
feet near Paris, France under a lease that expires in May 2005. The Company's
food testing business leases 10,237 square feet in Hopkinton, Massachusetts
under a lease that expires in January 1999.

SCIENTIFIC ADVISORY BOARD

The following individuals comprise Vysis' Scientific Advisory Board, which
plays an active role in guiding Vysis' research and development activities.

KURT HIRSCHHORN, M.D., is Professor of Pediatrics, Human Genetics and
Medicine, Mount Sinai School of Medicine, New York, New York. Dr. Hirschhorn is
a founding member of the American College of Medical Genetics; serves on the
Editorial Board or Committee of eight scientific journals; and has worked on IN
SITU hybridization since the early 1970's.

ROBERT B. JENKINS, M.D., PH.D., is Associate Professor of Laboratory
Medicine, and co-Director of the clinical Cytogenetics and clinical Molecular
Genetic Laboratories at the Mayo Clinic, Rochester, Minnesota. Dr. Jenkins is
the Associate Director of the Mayo Clinic's Cytogenetics Laboratory and has
on-going research programs into the molecular pathology of prostate, breast and
ovarian cancers and gliomas. Dr. Jenkins has published 43 scientific articles on
the use of FISH to assess cancer pathology.

FRED R. KRAMER, PH.D., is Chairman, Department of Molecular Genetics, Public
Health Research Institute, New York, New York. Dr. Kramer is the co-author of
over 30 scientific articles; is the inventor or co-inventor on fundamental
patents covering QBR based diagnostic assays, which are exclusively licensed to
the Company; and has led active research on QBR assays since 1985.

DAVID H. LEDBETTER, PH.D., is Professor of Genetics and Director of the
Center for Medical Genetics, University of Chicago, Chicago, Illinois. He served
as Chief, Diagnostic Development Branch of the National Center for Human Genome
Research at the National Institutes of Health from 1993 to May 1996, is a
Founding Fellow of the American College of Medical Genetics, is on the Editorial
Board of HUMAN MOLECULAR GENETICS and is also the Chairman of the Company's
Scientific Advisory Board.

KENNETH L. MELMON, M.D., is Professor of Medicine and Molecular
Pharmacology, Stanford University School of Medicine, Department of Medicine and
Clinical Pharmacology, Stanford, California. Dr. Melmon was the Arthur L.
Bloomfield Professor of Medicine at Stanford University School of Medicine from
1978-1988; was the Chairman from 1978 to 1984 and Associate Chairman from 1989
to 1993 of the Department of Medicine at Stanford University School of Medicine;
is the Associate Dean for Postgraduate Medical Education; and serves as an
Editorial Board member or consultant for six scientific journals.

DAVID H. PERSING, M.D., PH.D., is Associate Professor, Department of
Laboratory Medicine and Pathology and Department of Clinical Microbiology, Mayo
Clinic, Rochester, Minnesota. Dr. Persing leads active research into infectious
disease diagnosis by nucleic acid detection; is the inventor of two pending U.S.
patent applications on detection of particular pathogens by nucleic acid
amplification assays; and serves as a regular reviewer for the NEW ENGLAND
JOURNAL OF MEDICINE.

57
<PAGE>
DAN PINKEL, PH.D., is Professor, Department of Laboratory Medicine, UCSF
Cancer Center, University of California, San Francisco. Dr. Pinkel is the author
or co-author of over 50 publications on the uses of FISH; is the co-inventor of
U.S. patents on FISH probes for specific chromosomal locations and CGH; and
leads active research on gCGH assays.

HANS J. TANKE, PH.D., is Chairman, Department of Cytochemistry and
Cytometry, Sylvius Laboratory, Leiden University, Leiden, The Netherlands. Dr.
Tanke is the author or co-author of over 130 publications in the fields of
cytology and molecular biology; is a member of the Editorial Board of CYTOMETRY,
ANALYTICAL CELLULAR PATHOLOGY AND BIOIMAGING; is the Chairman of the EC Network
"FISH and Image Analysis"; and leads active research programs on detection of IN
SITU hybridization results.

STEPHEN T. WARREN, PH.D., is Investigator, Howard Hughes Medical Institute,
the William Patterson Timmie Professor of Human Genetics, and Professor of
Biochemistry and of Pediatrics at Emory University School of Medicine, Atlanta,
Georgia. Dr. Warren is a Founding Fellow of the American College of Medical
Genetics and is board certified in clinical cytogenetics and clinical molecular
genetics; is on the Editorial Boards of the AMERICAN JOURNAL OF MEDICAL
GENETICS, GENOMICS, MAMMALIAN GENOME, BIOCHEMICAL AND MOLECULAR MEDICINE, and
HUMAN MOLECULAR GENETICS; and leads active research into the molecular basis of
X chromosome-linked diseases and trinucleotide repeat expansion disorders.

58
<PAGE>
MANAGEMENT

DIRECTORS AND EXECUTIVE OFFICERS

The directors and executive officers of the Company, their ages as of
January 1, 1998 and their present positions with the Company are as follows:

<TABLE>
<CAPTION>
NAME AGE POSITION
- ------------------------------------ --- ---------------------------------------------------------------------
<S> <C> <C>
John L. Bishop...................... 53 President, Chief Executive Officer and Director
George R. Kennedy................... 44 Senior Vice President, Sales and Marketing
Russel K. Enns...................... 49 Vice President, Regulatory Affairs
James J. Habschmidt................. 42 Vice President of Finance and Chief Financial Officer
James P. Marcella................... 55 Vice President, Operations
William E. Murray................... 44 General Counsel and Secretary
Steven A. Seelig.................... 49 Vice President, Research and Development and Chief Medical Officer
Robert C. Carr...................... 57 Chairman of the Board of Directors
William M. Bartlett................. 65 Director
Kenneth L. Melmon................... 63 Director
Walter R. Quanstrom................. 55 Director
Frank J. Sroka...................... 49 Director
Richard C. Williams................. 54 Director
</TABLE>

All Directors are elected to serve until the next annual meeting of
stockholders and until their successors are elected and qualified. Officers
serve at the pleasure of the Board of Directors.

MR. JOHN L. BISHOP has served as President and as a Director since November
1993 and became Chief Executive Officer in February 1996. Mr. Bishop has over 25
years experience in developing and operating diagnostics businesses. From 1991
until November 1993, Mr. Bishop was Chairman and Chief Executive Officer of
MicroProbe Corporation, a manufacturer of DNA probe diagnostics and therapeutics
and, from 1987 until 1991 of Source Scientific Systems, an original equipment
manufacturer of automated diagnostic systems. From 1984 until 1986, Mr. Bishop
was President and Chief Operating Officer of Gen-Probe, Inc., a developer and
manufacturer of DNA probe diagnostics for infectious diseases. From 1968 until
1984, Mr. Bishop held various management positions with American Hospital Supply
Company and its affiliates, including a three year assignment in Japan as an
Executive Vice President and Chief Executive Officer of International Reagents
Corp., a joint venture between American Hospital Supply Company and Green Cross
Corporation.

MR. GEORGE R. KENNEDY has served as Senior Vice President, Sales and
Marketing since September 1997. From April 1996 to September 1997 he served as
Vice President, Sales and Marketing. Prior to joining the Company in April 1996,
Mr. Kennedy was Director of Sales and Marketing of Difco Laboratories, a
microbiology diagnostic products manufacturer, from June 1992 to April 1996.
From May 1990 to June 1992, Mr. Kennedy was Director of Marketing for Dianon
Systems, Inc., an oncology reference laboratory.

DR. RUSSEL K. ENNS, PH.D. has served as Vice President, Regulatory Affairs
since he joined the Company in December 1995. Prior to joining the Company, Dr.
Enns was Vice President of Technical Affairs of MicroProbe Corporation from
February 1992 to November 1995. From August 1984 to February 1992, Dr. Enns held
several positions with Gen-Probe, Inc., including Director of Product
Development and Clinical Development and Director, Technical Affairs.

MR. JAMES J. HABSCHMIDT became Vice President of Finance and Chief Financial
Officer in November 1997. From September 1993 until November 1997, Mr.
Habschmidt served as Vice President,

59
<PAGE>
Development & Finance and Chief Financial Officer of Rand McNally & Co., a maker
and publisher of maps. From January 1991 to September 1993 he served as
Executive Vice President Operations & Finance of Silvestri Corporation, a
designer and marketer of home accessories. From 1986 until 1991, Mr. Habschmidt
was Vice President, Finance and Administration of Kewaunee Scientific
Corporation, a developer and manufacturer of laboratory equipment, furnishings
and accessories. From 1982 until 1986 he served in financial management
positions at American Hospital Supply Company prior to and after its acquisition
by Baxter International, a diagnostic product manufacturer.

MR. JAMES P. MARCELLA has served as Vice President, Operations since March
1994. Prior to then Mr. Marcella held various managerial positions in
manufacturing and operations with the Company since December 1991. From April
1990 to December 1991 he served as Chief Executive Officer of Betagen
Corporation, a biotechnology company.

MR. WILLIAM E. MURRAY, J.D., has served as Vice President and Secretary of
the Company since March 1994 and Assistant Secretary of the Company from
September 1992 to March 1994, while employed by Amoco. In January 1996, Mr.
Murray joined the Company as an executive officer, assuming the additional role
of General Counsel. Mr. Murray served from 1983 through 1995 in Amoco's Law
department in both attorney and patent attorney positions.

DR. STEVEN A. SEELIG, M.D., PH.D., has served as Vice President, Research
and Development and Chief Medical Officer since February 1996. He has held
various research management positions with the Company and its predecessors
since May 1989. Dr. Seelig was Associate Professor and Director of pediatric
endocrinology and metabolism at the University of Minnesota from 1985 to 1989.

MR. ROBERT C. CARR was appointed to the Board of Directors of the Company in
October 1993 and was elected Chairman of the Company's Board of Directors in
February 1997. Mr. Carr has served as President of ATC since October 1993. Mr.
Carr joined Amoco in 1990 and has held various positions with Amoco, including
Vice President of Chemicals Development and Diversification, Vice President and
Treasurer, Vice President of Planning and Administration, and Vice President and
Controller. He has served as Vice President Corporate Planning since May 1997.

MR. WILLIAM M. BARTLETT has been a Director since September 1997. For more
than the last five years, Mr. Bartlett has served as a consultant to various
companies in the healthcare industry. Mr. Bartlett is a director of Medco
Research, Inc., an adenosine technology and cardiovascular development company,
and a director and Vice Chairman of Medicor Corporation, a privately held
manufacturer of minimally invasive surgical instruments. Mr. Bartlett has a
significant amount of experience in the health care industry, having been Chief
Executive Officer--Medical Products Group and Corporate Vice President for G.D.
Searle & Co., a manufacturer and distributor of hospital equipment and
diagnostic equipment from 1978 to 1982. He was also President, Atlantic
International Division of American Hospital Supply Company from 1975 to 1978 and
of the V. Mueller Surgical Instrument Division from 1971 to 1975.

DR. KENNETH L. MELMON, M.D., has been a Director since September 1997. Mr.
Melmon has been a Scientific Advisory Board member of the Company since August
1994. He is also a director of Epoch, Inc. a biotechnology corporation. Since
July 1994 he has been Associate Dean, Postgraduate Medical Education at Stanford
University School of Medicine. Dr. Melmon was Associate Chairman, Department of
Medicine at the Stanford University School of Medicine from July 1989 to July
1993 and was Chairman, Stanford University Hospital Technology Transfer Program
from July 1988 to July 1993. He was Chairman, Department of Medicine at the
Stanford University School of Medicine from 1978 to 1984 and has been Professor
of Medicine and Molecular Pharmacology since 1978.

DR. WALTER R. QUANSTROM, PH.D., has been a Director since September 1997.
Dr. Quanstrom is presently Vice President of Environment, Health and Safety and
has held such position with Amoco since 1987.

60
<PAGE>
MR. FRANK J. SROKA, J.D., was appointed to the Board of Directors of the
Company in September 1993. Mr. Sroka has served as General Attorney for Amoco
with responsibility for the legal matters of ATC and its subsidiaries since
September 1993. Prior to such position, Mr. Sroka held positions in the
Research, Patents & Licensing and Law departments of Amoco since 1970.

MR. RICHARD C. WILLIAMS has been a Director since September 1997. Mr.
Williams has served as President of Connor-Thoele Limited, a consulting and
financial advisory firm which serves the healthcare and pharmaceuticals industry
since March 1989. Mr. Williams has served as Chairman of the Board of Directors
since October 1992 and as a director of Medco Research, Inc. since January 1991,
as a director of Centaur, Inc., a private equine diagnostic company, since
January 1991 and as a director of Immunomedics, Inc., a biopharmaceutical
research company, since March 1993. Prior to these positions Mr. Williams has
gained extensive experience in the healthcare industry, most notably as Vice
President and Chief Financial Officer of Erbamont, N.V., a pharmaceutical
company, and at Abbott Laboratories and American Hospital Supply Company where
he held a variety of financial management positions.

The Board of Directors has established Audit and Compensation Committees.
The members of the Audit Committee are Messrs. Bartlett, Sroka and Williams. The
Audit Committee is empowered by the Board of Directors to review the financial
books and records of the Company in consultation with the Company's accounting
staff and its independent auditors and to review with the accounting staff and
independent auditors any questions raised with respect to accounting and
auditing policy and procedure. The members of the Compensation Committee are
Messrs. Bartlett, Carr, Melmon, and Williams. The Compensation Committee will
make recommendations to the Board of Directors as to general levels of
compensation for all employees of the Company and the annual salary of each of
the executive officers of the Company. In addition, the Compensation Committee
will grant options to employees under the Company's option plan, and review and
approve compensation and benefit plans of the Company.

61
<PAGE>
EXECUTIVE COMPENSATION

The following table sets forth the amounts paid by the Company during the
fiscal year indicated to (i) the Company's Chief Executive Officer (the "CEO")
and (ii) the four other most highly compensated executive officers (the "Named
Executive Officers") whose compensation exceeded $100,000 for services rendered
to the Company.

<TABLE>
<CAPTION>
STOCK ALL OTHER
NAMES AND PRINCIPAL POSITION YEAR SALARY BONUS OPTIONS# COMPENSATION(1)
- ------------------------------------------------------ --------- ---------- --------- ----------- ----------------
<S> <C> <C> <C> <C> <C>
John L. Bishop........................................ 1997 $ 224,035 $ 25,000 -- $ 4,750
President and 1996 210,000 36,500 131,387 18,946
Chief Executive Officer

George R. Kennedy..................................... 1997 153,877 -- 7,300 3,468
Senior Vice President 1996 123,258 -- 36,497 36,480
Sales and Marketing

Steven A. Seelig...................................... 1997 138,910 -- -- 2,240
Vice President 1996 130,200 -- 65,694 4,007
Research and Development and
Chief Medical Officer

James P. Marcella..................................... 1997 129,385 -- -- 3,882
Vice President 1996 125,000 15,000 32,847 3,822
Operations

Russel K. Enns........................................ 1997 116,654 -- 10,949 74,219
Vice President 1996 110,000 -- 21,898 635
Regulatory Affairs
</TABLE>

- ------------------------

(1) Amounts represent the Company's 401(k) contributions made on behalf of each
of the named individuals and the reimbursement of 1996 relocation expenses
in the amounts of $14,446 for Mr. Bishop and $34,305 for Mr. Kennedy and
1997 relocation expenses in the amount of $74,219 for Dr. Enns.

DIRECTOR COMPENSATION

Messrs. Bartlett, Melmon and Williams each receive a fee of $2,000 per month
and $2,000 per board meeting attended. None of the remaining directors receive
any compensation for serving on the Board of Directors.

62
<PAGE>
STOCK OPTION GRANTS IN LAST FISCAL YEAR

The following table summarizes options to purchase shares of the Company's
common stock granted during the fiscal year ended December 31, 1997 to the
Company's CEO and the Named Executive Officers. The amounts shown as potential
realizable values on the options identified in the table are based on assumed
annualized rates of appreciation in the price of the Common Stock of five
percent and ten percent over the term of the options, as set forth in the rules
of the Securities and Exchange Commission. Actual gains, if any, on stock option
exercises depend on the future performance of the common stock. There can be no
assurance that the potential realizable values reflected in this table will be
achieved.

<TABLE>
<CAPTION>
POTENTIAL REALIZED
VALUE AT ASSUMED
NUMBER OF ANNUAL RATES OF STOCK
SHARES % OF TOTAL PRICE APPRECIATION
UNDERLYING OPTIONS GRANTED FOR OPTION TERM
OPTIONS TO EMPLOYEES IN EXERCISE EXPIRATION ---------------------
NAME GRANTED FISCAL YEAR PRICE DATE 5% 10%
- -------------------------------------- ----------- --------------- ----------- ----------- --------- ----------

<S> <C> <C> <C> <C> <C> <C>
George R. Kennedy..................... 7,300 4.5% $ 6.85 8/29/07 $ 31,448 $ 79,695

Russel K. Enns........................ 10,949 2.5 6.85 8/29/07 47,168 119,532
</TABLE>

AGGREGATE OPTION EXERCISES IN LAST FISCAL YEAR AND FISCAL YEAR-END OPTION VALUES

The following table sets forth for the Company's CEO and the Named Executive
Officers aggregated information concerning each exercise of stock options during
the fiscal year ended December 31, 1997, and the fiscal year-end value of
unexercised options.

<TABLE>
<CAPTION>
NUMBER OF
UNEXERCISED VALUE OF UNEXERCISED
OPTIONS AT IN-THE-MONEY OPTIONS
FISCAL YEAR-END AT FISCAL YEAR-END
(#) ($)(1)
---------------- --------------------
SHARES ACQUIRED VALUE EXERCISABLE/ EXERCISABLE/
NAME ON EXERCISE (#) REALIZED ($) UNEXERCISABLE UNEXERCISABLE
- -------------------------------------------------- --------------- ------------- ---------------- --------------------

<S> <C> <C> <C> <C>
John L. Bishop.................................... -- -- 71,181/60,206 $ 887,627/750,769

Steven A. Seelig.................................. -- -- 35,591/30,103 443,820/375,384

James P. Marcella................................. -- -- 17,796/15,051 221,916/187,686

George R. Kennedy................................. -- -- 15,970/27,827 199,146/300,867

Russel K. Enns.................................... -- -- 11,864/20,983 147,944/192,460
</TABLE>

- ------------------------

(1) Based on a December 31, 1997 estimate of fair market value of $13.00 per
share.

STOCK INCENTIVE PLAN

The Company has adopted and the stockholder of the Company has approved, the
Vysis, Inc. 1996 Stock Incentive Plan (the "Stock Incentive Plan"). The
committee appointed under the Stock Incentive Plan may make awards of stock
options (both incentive and nonqualified) and rights to purchase shares of
restricted stock to officers, employees, board members and service providers of
the Company; provided, however, that incentive stock options ("ISOs") can be
awarded only to officers or other key employees of the Company.

Options may be granted at not less than 100% of the fair market value of the
Common Stock of the Company on the date of grant (or 110% of the fair market
value if the option is an ISO and the grantee is a 10% shareholder of the
Company or its affiliates). Options granted under the Incentive Plan are
generally exercisable for a period specified at the time of grant, not to exceed
10 years from the date of grant

63
<PAGE>
(5 years for an ISO granted to a 10% shareholder). ISOs are also subject to
other requirements imposed by section 422 of the Internal Revenue Code of 1996.

Upon a change in control of the Company (as defined in the Stock Incentive
Plan), all unexercised stock options and purchase rights shall become fully
exercisable.

The maximum number of shares of Common Stock reserved for issuance under the
Stock Incentive Plan is 985,402 shares, subject to adjustment as provided in the
Stock Incentive Plan to reflect certain corporate transactions affecting the
number or type of outstanding shares.

CONSULTING AGREEMENTS

Prior to their appointment to the Board of Directors in September 1997, each
of Messrs. Bartlett, Melmon and Williams was a party to an advisory board
consulting agreement with the Company pursuant to which each of such individuals
provided consulting services to the Company through service on the Company's
advisory board. Such advisory board had been maintained since August 1994 for
the purpose of rendering informal advice to the Company regarding medical and
technology issues as well as business, operational and financial matters. Under
such consulting agreements, these individuals were paid in cash the following
amounts in 1994, 1995, 1996 and through September 30, 1997, respectively: Mr.
Bartlett, $18,136, $36,717, $87,572 and $45,733; Mr. Melmon, $13,552, $53,891,
$82,396 and $35,283; and Mr. Williams, $19,323, $37,979, $64,236 and $52,344.
(In the case of Mr. Williams, the amounts shown include amounts paid to
Conner-Thoele Limited, an advisory firm of which Mr. Williams is president).
Such consulting agreements have been terminated.

In addition, as consideration for rendering services relating to attendance
at meetings of the Board of Directors, the Company granted during 1996 to each
of Messrs. Bartlett, Melmon and Williams, options to purchase 18,249 shares of
Common Stock at an exercise price of $0.53 per share. In February 1997, such
individuals were granted additional options to purchase an aggregate of 25,549
shares of Common Stock at an exercise price of $2.74 per share as follows: Mr.
Bartlett, 7,300 shares; Mr. Melmon, 10,949 shares; and Mr. Williams, 7,300
shares. Mr. Melmon also was granted options to purchase 1,095 shares of Common
Stock in each of 1996 and 1997, with exercise prices of $0.53 and $2.74 per
share, respectively, as consideration for rendering consulting services as a
member of the Company's Scientific Advisory Board.

COMPENSATION COMMITTEE

Compensation information with respect to the Company's CEO and the Named
Executive Officers for 1996 reflects compensation earned while the Company was
an indirect, wholly owned subsidiary of Amoco. During 1996, the Company had no
compensation committee. Executive compensation levels during 1996 were
established by the Company's Board of Directors. Executive compensation levels
for 1997 were also established by the Company's Board of Directors prior to the
formation of the compensation committee in October 1997.

64
<PAGE>
PRINCIPAL STOCKHOLDER AND SECURITIES OWNERSHIP OF MANAGEMENT

OWNERSHIP OF COMPANY COMMON STOCK

The following table sets forth certain information regarding the beneficial
ownership of Common Stock by each person known by the Company to be the
beneficial owner of 5% or more of the outstanding Common Stock, by each of the
Company's directors and the Named Executive Officers and by all directors and
executive officers of the Company as a group, as of January 1, 1998, and as
adjusted for the sale by the Company of the shares in the offering. The
beneficial ownership reflected in the following table is calculated in
accordance with Section 13(d) of the Exchange Act after giving effect to the
conversion of all outstanding Preferred Stock into Common Stock. Unless
otherwise indicated, ownership includes sole voting and investment power.

<TABLE>
<CAPTION>
SHARES BENEFICIALLY OWNED SHARES BENEFICIALLY
OWNED AFTER THE
BEFORE THE OFFERING(1) OFFERING(1)
-------------------------- ---------------------
NAME NUMBER PERCENT NUMBER PERCENT
- ------------------------------------------------------------------ ------------- ----------- ---------- ---------
<S> <C> <C> <C> <C>
Amoco Corporation................................................. 5,987,682(2) 99.8% 5,987,682 63.0%
200 East Randolph Drive
Chicago, Illinois 60601

John L. Bishop.................................................... 79,395 1.3 79,395 *

Russel K. Enns.................................................... 13,233 * 13,233 *

George R. Kennedy................................................. 17,491 * 17,491 *

James P. Marcella................................................. 19,849 * 19,849 *

Steven A. Seelig.................................................. 39,698 * 39,698 *

William M. Bartlett............................................... 10,724 * 10,724 *

Robert C. Carr.................................................... -- * -- *

Kenneth L. Melmon................................................. 10,724 * 10,724 *

Walter R. Quanstrom............................................... -- * -- *

Frank J. Sroka.................................................... -- * -- *

Richard C. Williams............................................... 10,724 * 10,724 *

Directors and Executive Officers as a Group (12 persons).......... 210,660 3.4 210,660 2.2
</TABLE>

- ------------------------

* Less than 1%

(1) Except in the case of Amoco, shares listed as beneficially owned represent
shares subject to options granted by the Company, which are exercisable
within 60 days of January 1, 1998.

(2) Includes 1,058,394 outstanding shares of Common Stock and 4,929,288 shares
of Common Stock issuable upon conversion of the Company's outstanding Series
A and Series B Preferred Stock. All such shares of Common Stock and
Preferred Stock are owned of record by ATC, a wholly owned subsidiary of
Amoco.

65
<PAGE>
OWNERSHIP OF PARENT STOCK

The following table sets forth at October 6, 1997, the ownership of common
stock, no par value per share, of Amoco Corporation by the Company's directors,
the Named Executive Officers, and all directors and executive officers of the
Company as a group. Unless otherwise indicated, the persons named below have
sole voting and investment power with respect to the shares beneficially owned
by them. The directors and executive officers of Vysis own in the aggregate less
than one percent of the common stock of Amoco Corporation.

<TABLE>
<CAPTION>
TOTAL SHARES
BENEFICIALLY
NAME OWNED(1)
- -------------------------------------------------------------------------------------------- --------------------
<S> <C>
John L. Bishop.............................................................................. 55
Russel K. Enns.............................................................................. --
George R. Kennedy........................................................................... --
James P. Marcella........................................................................... --
Steven A. Seelig............................................................................ 3,636
William M. Bartlett......................................................................... --
Robert C. Carr.............................................................................. 59,547
Kenneth L. Melmon........................................................................... --
Walter R. Quanstrom(2)...................................................................... 71,956
Frank J. Sroka(3)........................................................................... 29,550
Richard C. Williams......................................................................... --
Directors and Executive Officers as a Group (12 persons)(2)(3).............................. 167,172
</TABLE>

- ------------------------

(1) The share amounts include those shares as to which the following persons had
a right to acquire beneficial ownership by exercising stock options as of
October 6, 1997, or within 60 days after that date: Mr. Seelig, 800 shares;
Mr. Carr, 59,500 shares; Mr. Quanstrom, 55,000 shares; Mr. Sroka, 19,800;
and all directors and executive officers as a group, 135,100 shares. Also
included are shares owned in the Amoco Performance Share Plan and those
allocable to the Amoco Stock Fund accounts of participants in the Amoco
Employee Savings Plan.

(2) Includes 500 shares as to which Mr. Quanstrom shares voting and dispositive
authority.

(3) Includes 2,068 shares as to which Mr. Sroka shares voting and dispositive
authority.

66
<PAGE>
CERTAIN TRANSACTIONS

Prior to the consummation of this offering, the Company operated as a
subsidiary of Amoco. In connection therewith, the Company engaged in a variety
of transactions with Amoco and may continue to do so on a more limited basis in
the future.

The Company has in the past received certain legal services (internal and
external), research and development support, and administrative support from
Amoco and has paid for such services and support on an actual usage or pro rata
basis. The amount of these costs allocated to the Company aggregated
$11,569,000, $3,058,000, $304,000 and $142,000 in 1994, 1995, 1996 and the nine
months ended September 30, 1997, respectively. Amoco has informed the Company
that it does not intend to provide any such services or support after completion
of this offering. In addition, the Company received funding requirements and
assets from Amoco.

The costs of these services, funding requirements and asset transfers were
accounted for by Amoco as intercompany receivables from Vysis. These receivables
were periodically converted into equity of Vysis. This investment by Amoco in
the Company aggregated $22,445,000, $15,384,000 and $2,315,000 in 1994, 1995 and
1996. Additionally in 1996, such amounts were also represented by a note payable
to Amoco. At December 31, 1996, the balance of the note payable was $5,106,000.
This note was subsequently converted into 553,126 shares of Series B Preferred
Stock. In 1997, the sharing of costs and funding has continued, with the
aggregate amount of such costs and funding represented by a promissory note that
bears interest at 7.5% per annum. As of December 31, 1997, the balance of the
note payable is approximately $11.2 million due from the Company to Amoco. Amoco
will fund ongoing cash requirements through the completion of this offering
resulting in an increase to the 1997 note payable. This note will not be
converted into equity but will be retired with a portion of the proceeds of this
offering. Amoco has advised the Company that it does not intend to continue such
funding after completion of this offering. See "Use of Proceeds."

The Company and Amoco will enter into a Cooperation Agreement, which sets
out the terms on which Amoco and the Company will cooperate after the closing of
this offering in handling various matters. These matters include (i)
documentation of the assignment to the Company of certain intellectual property
rights, (ii) the Gen-Probe litigation, (iii) retention by Amoco of certain
liabilities relating to ATC's discontinued operations, and (iv) access to
Amoco's and the Company's business records. See "Business--Litigation."

Prior to the completion of this offering, the Company has been included in
the consolidated or combined federal and state income tax returns of Amoco. For
periods after the completion of this offering, the Company will no longer be
included in Amoco's federal consolidated returns, although it may continue to be
included in one or more state or local combined returns. Pursuant to a Tax
Allocation Agreement, for periods during which the Company is included in
Amoco's federal consolidated return, the Company generally receives no credit
for tax benefits accruing during such periods to other members of the Amoco
consolidated group as a result of any deductions or losses incurred by the
Company; except that beginning in 1996, debt obligations of the Company owed to
Amoco are to be reduced by approximately 35% of the Company's estimated income
or loss for income tax purposes, resulting in an aggregate reduction of the
Company's debt to Amoco with an offsetting increase to contributed capital of
approximately $5.0 million for 1996 and $4.1 million for the first nine months
of 1997. Subsequent to the completion of this offering, the Company will no
longer be included in the consolidated federal tax return of Amoco.

Under state tax laws in a number of states, including Illinois (the state in
which much of the Company's business is taxed), the Company is required by law
to be included in Amoco's unitary state tax returns as long as Amoco owns or
controls 50% or more of the voting equity of the Company. Immediately subsequent
to this offering, Amoco will own approximately 63% of the voting equity. Under
the Tax Allocation Agreement, for tax periods subsequent to this offering, the
Company pays Amoco, or Amoco pays the Company, as the case may be, an amount
determined on the basis of a comparison between the

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actual combined tax liability of Amoco and the liability that would have arisen
had the Company been excluded from Amoco's unitary return. For tax periods prior
to this offering, the Company's state tax liability is determined by Amoco based
upon their internal allocation methodology. The application of this methodology
resulted in a charge to the Company of $53,000 for unitary state taxes in 1996.
Such charge, if any, for state income taxes from the period January 1, 1997
through the effective date of this offering will also be immaterial. In
addition, in such unitary states the Company will not have the future benefit of
tax loss carry-forwards that would have arisen but for the legal requirement
that the Company be included in Amoco's unitary tax return.

Immediately prior to the completion of this offering, Vysis and Amoco will
enter into a registration rights agreement (the "Registration Agreement")
pursuant to which Vysis will grant Amoco registration rights under the
Securities Act with respect to the shares of Common Stock owned by Amoco. Under
the Registration Agreement, Amoco will have the right commencing 180 days after
the date of this Prospectus to demand that the Company register its shares under
the Securities Act. However, Amoco has agreed with the Underwriters that it will
not sell any shares of Common Stock for a period of one year following the date
of this Prospectus without the prior written consent of Furman Selz LLC. See
"Underwriting." Under the Registration Agreement, Amoco may only sell securities
under one effective demand registration per calender year and the right may only
be exercised with respect to specified minimum amounts of shares of Common
Stock. The Company may postpone such a demand under certain circumstances. Amoco
will have the right to include shares of Common Stock owned by it in any
registration proposed by the Company under the Securities Act, subject to
certain limitations.

Three current directors of the Company (Messrs. Bartlett, Melmon and
Williams) have provided consulting services to the Company from time to time.
See "Management--Consulting Agreements."

DESCRIPTION OF CAPITAL STOCK

The authorized capital stock of the Company consists of 35,000,000 shares of
Common Stock, $0.001 par value, and 10,000,000 shares of Preferred Stock, $0.001
par value. Upon completion of this offering there will be 9,501,260 shares of
Common Stock outstanding (10,026,260 shares if the Underwriters' over-allotment
option is exercised in full), and no shares of Preferred Stock outstanding. The
authorized and unissued shares of the Preferred Stock and Common Stock may be
utilized for a variety of corporate purposes, including future public offerings
and corporate acquisitions, and could be utilized, under certain circumstances,
as a method of preventing or making more difficult a takeover or change in
control of the Company.

COMMON STOCK

Prior to completion of the offering 1,071,972 shares of Common Stock were
issued and outstanding and were held of record by six holders. All such shares
are validly issued, fully paid and nonassessable. All shares of Common Stock are
entitled to participate in dividends, subject to preference rights of holders of
the Preferred Stock, when, as and if declared by the Board of Directors out of
funds legally available therefor, are entitled to participate equally in the
assets of the Company, after paying or setting aside sufficient assets to fully
pay the preferential amounts owed to holders of Preferred Stock, in the event of
liquidation, and have no right of conversion, redemption, preemptive or
preferential rights to subscribe for any additional shares of any class of
capital stock of the Company, whether now or hereafter authorized. Holders of
Common Stock are entitled to one vote per share on all matters submitted to a
vote of the stockholders. Such voting rights are non-cumulative, so that
stockholders holding more than 50% of the outstanding shares entitled to vote
are able to elect all members of the Board of Directors. See "Risk
Factors--Continued Control by Principal Stockholder."

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PREFERRED STOCK

No shares of Preferred Stock will be outstanding after this offering. The
Board of Directors is authorized to issue, by resolution and without any action
by stockholders, up to 10,000,000 shares of Preferred Stock and may establish
the designations, dividend rights, conversion rights, voting rights, terms of
redemption, liquidation preference, sinking fund terms and all other
preferences, relative rights and limitations of the shares of each series of
Preferred Stock.

SERIES A CONVERTIBLE PREFERRED STOCK.

Prior to the completion of this offering, 6,200,000 shares of Preferred
Stock are issued and outstanding, designated as Series A Preferred Stock.

CONVERSION INTO COMMON STOCK. Each share of Series A Preferred Stock is
convertible at any time, at the option of the holder, into shares of Common
Stock. The Series A Preferred Stock will automatically convert into an aggregate
of 4,525,547 shares of Common Stock upon completion of this offering.

VOTING RIGHTS. Each share of Series A Preferred Stock is entitled to a
number of votes per share equal to the number of shares of Common Stock into
which such share is then convertible. Each holder of Series A Preferred Stock is
entitled to vote on all matters submitted to a vote of the holders of the Common
Stock, voting together as a single class.

DIVIDENDS. Holders of Series A Preferred Stock are entitled to receive,
before any dividends are declared and set aside for any class or series of stock
ranking as to dividends or upon liquidation junior to the Series A Preferred
Stock, when, as and if declared by the Board of Directors, dividends in cash
equal to six percent per annum times the liquidation preference (initially
$8.064) per share. Such dividends are cumulative, and unless such cumulative
dividends are paid, no sums may be set aside for or applied to the purchase or
redemption of, and no dividends may be declared or paid or any other
distribution ordered or made upon, any shares of any class or series of stock
ranking as to dividends or upon liquidation junior to the Series A Preferred
Stock. Holders of Series A Preferred Stock are also entitled to share in any
dividends paid on the Common Stock in an amount equal to the product of the per
share amount of such dividend times the number of shares of Common Stock into
which such Series A Preferred Stock is then convertible.

LIQUIDATION RIGHTS. In the event of any liquidation, dissolution or winding
up of the Company, whether voluntary or involuntary, the holders of Series A
Preferred Stock are entitled to receive out of the assets of the Company legally
available for distribution to stockholders, prior and in preference to any
distribution of any assets to the holders of Common Stock or any stock ranking
junior in liquidation to the Series A Preferred Stock, the sum of $8.064 per
share plus any unpaid dividends with respect to such shares. If the assets of
the Company available for distribution are insufficient to pay the holders of
Series A Preferred Stock the amounts to which they are entitled, the holders of
Series A Preferred Stock share ratably in any such distribution of assets. After
payment to the holders of Series A Preferred Stock as described above, the
entire remaining assets of the Company legally available for distribution are to
be distributed among the holders of the Series A Preferred Stock and the Common
Stock in proportion to number of shares of Common Stock into which such Series A
Preferred shares are convertible, or the number of shares of Common Stock held
by such holders, as the case may be.

SERIES B CONVERTIBLE PREFERRED STOCK.

Prior to the completion of this offering, 553,126 shares of Preferred Stock
are issued and outstanding, designated as Series B Preferred Stock. The Series B
Preferred Stock is identical to the Series A Preferred Stock except that the
liquidation preference of the Series B Preferred Stock is equal to $9.23 per
share. The Series B Preferred Stock will automatically convert into an aggregate
of 403,741 shares of Common Stock upon completion of this offering.

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<PAGE>
DELAWARE ANTI-TAKEOVER LAW

The Company is a Delaware corporation that is subject to Section 203 of the
Delaware General Corporation Law ("Section 203"). Under Section 203 certain
"business combinations" between a Delaware corporation, whose stock generally is
publicly traded or held of record by more than 2,000 stockholders, and an
"interested stockholder" are prohibited for a three-year period following the
date that such stockholder became an interested stockholder, unless (i) the
corporation has elected in its certificate of incorporation not to be governed
by Section 203 (the Company has not made such election), (ii) the business
combination was approved by the board of directors of the corporation before the
other party to the business combination became an interested stockholder, (iii)
upon consummation of the transaction that made it an interested stockholder, the
interested stockholder owned at least 85% of the voting stock of the corporation
outstanding at the commencement of the transaction (excluding voting stock owned
by directors who are also officers or held in employee benefit plans in which
the employees do not have a confidential right to tender or vote stock held by
the plan) or (iv) the business combination is approved by the board of directors
of the corporation and ratified by two-thirds of the voting stock which the
interested stockholder did not own. The three-year prohibition also does not
apply to certain business combinations proposed by an interested stockholder
following the announcement or notification of certain extraordinary transactions
involving the corporation and a person who had not been an interested
stockholder during the previous three years or who became an interested
stockholder with the approval of a majority of the corporation's directors. The
term "business combination" is defined generally to include mergers or
consolidations between a Delaware corporation and an interested stockholder,
transactions with an interested stockholder involving the assets or stock of the
corporation or its majority-owned subsidiaries, and transactions which increase
an interested stockholder's percentage ownership of stock. The term "interested
stockholder" is defined generally as those stockholders who become beneficial
owners of 15% or more of a Delaware corporation's voting stock, together with
the affiliates or associates of that stockholder.

TRANSFER AGENT AND REGISTRAR

The transfer agent and registrar for the Company's Common Stock is First
Chicago Trust Company of New York.

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SHARES ELIGIBLE FOR FUTURE SALE

Prior to this offering, there has been no market for the Common Stock.
Future sales of substantial amounts of Common Stock in the public market
following this offering could adversely affect the prevailing market price of
the Common Stock.

Upon completion of this offering, the Company will have 9,501,260 shares of
Common Stock outstanding. Of these shares, the 3,500,000 shares sold in the
offering will be freely tradeable without restriction under the Securities Act,
except any shares purchased by persons deemed to be "affiliates" of the Company
which will be subject to certain resale limitations of Rule 144 under the
Securities Act. The remaining shares, all but 13,578 of which will be owned by
Amoco, will be "restricted securities" within the meaning of Rule 144 and may
not be sold unless registered under the Securities Act or sold in accordance
with an exemption therefrom, such as Rule 144 or Rule 701 thereunder.

In general, under Rule 144, as currently in effect, if a period of at least
one year has elapsed between the later of the date on which "restricted
securities" were acquired from the Company or an "affiliate" of the Company then
the holder of such restricted securities is entitled to sell a number of shares
within any three-month period that does not exceed the greater of (i) one
percent of the then outstanding shares of the Common Stock (approximately 95,000
after the offering) or (ii) the average weekly reported volume of trading of the
Common Stock during the four calendar weeks preceding such sale. Sales under
Rule 144 are also subject to certain requirements pertaining to the manner of
such sales, notices of such sales and the availability of current public
information concerning the Company. Affiliates of the Company may sell shares
not constituting restricted shares in accordance with the foregoing volume
limitations and other requirements but without regard to the one-year period.
Under Rule 144(k), if a period of at least two years has elapsed between the
later of the date on which restricted shares were acquired from the Company or
the date on which they were acquired from an affiliate of the Company, a holder
of such restricted shares who is not an affiliate of the Company at the time of
the sale and has not been an affiliate of the Company for at least three months
prior to the sale would be entitled to sell the shares immediately without
regard to the volume limitations and other conditions described above. Amoco is
an affiliate of the Company and could begin selling shares of Common Stock of
the Company owned by it pursuant to Rule 144 subject to the volume restrictions
described above.

Rule 701 may be relied upon with respect to the resale of securities
originally purchased from the Company by its employees, directors, officers,
consultants or advisers prior to the closing of this offering, pursuant to
written compensatory benefit plans or written contracts relating to the
compensation of such persons. Securities issued in reliance on Rule 701 are
restricted securities and, beginning 90 days after the date of this Prospectus,
may be sold by non-affiliates subject only to the manner of sale provisions of
Rule 144, and by affiliates under Rule 144 without compliance with its one-year
minimum holding period requirement.

The Company has agreed that during the period beginning from the date of
this Prospectus and continuing to and including the date 180 days after the date
of this Prospectus, not to offer, sell, contract to sell or otherwise dispose of
any shares of Common Stock, any securities of the Company that are substantially
similar to the shares of the Common Stock or that are convertible or
exchangeable into securities that are substantially similar to the shares of the
Common Stock (other than pursuant to the Company's employee stock option plans)
without the prior written consent of Furman Selz LLC, except for the shares of
Common Stock offered in connection with this offering. The Company has also
agreed to require, pursuant to its rights under the Stock Incentive Plan, that
each option holder not sell or otherwise transfer or dispose of any shares of
Common Stock acquired upon exercise of such holders' options, without the prior
written consent of Furman Selz LLC, during the same 180 day period. Amoco has
agreed that during the period beginning from the date of this Prospectus and
continuing to and including the date one year after the date of this Prospectus,
not to offer, sell, contract to sell or otherwise dispose of any shares of
Common Stock, any securities of the Company that are substantially similar to
the shares of

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Common Stock or that are convertible or exchangeable into Common Stock or
securities, which are substantially similar to the shares of Common Stock
without the prior written consent of Furman Selz LLC. See "Underwriting."

The Company will grant Amoco registration rights with respect to shares of
Common Stock owned by Amoco. See "Certain Transactions."

The Company intends to file, shortly after completion of this offering, a
registration statement covering all 985,402 shares of Common Stock reserved for
issuance under the Stock Incentive Plan. Following the registration of such
shares, all shares purchased under such plan will be available for resale to the
public market without restriction, except that affiliates of the Company must
comply with the provisions of Rule 144 other than the holding period
requirement.

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UNDERWRITING

Each of the Underwriters named below (collectively, the "Underwriters"), for
which Furman Selz LLC, Deutsche Morgan Grenfell Inc. and EVEREN Securities, Inc.
are acting as representatives (the "Representatives"), have severally agreed,
subject to the terms and conditions set forth in the underwriting agreement
dated as of , 1998 (the "Underwriting Agreement"), to purchase, and
the Company has agreed to sell to each of the Underwriters, the aggregate number
of shares of Common Stock set forth opposite its name below:

<TABLE>
<CAPTION>
NUMBER OF
NAME SHARES
- --------------------------------------------------------------------------------- ----------
<S> <C>
Furman Selz LLC..................................................................
Deutsche Morgan Grenfell Inc.....................................................
EVEREN Securities, Inc...........................................................

----------
Total........................................................................ 3,500,000
</TABLE>

The Underwriting Agreement provides that the obligations of the several
Underwriters are subject to the approval of certain legal matters by counsel and
various other conditions. The nature of the Underwriters' obligations is such
that they are committed to purchase all of the above shares if any are
purchased. The Representatives have advised the Company that the Underwriters
propose to offer the shares of Common Stock directly to the public at the public
offering price set forth on the cover page of this Prospectus and to certain
dealers at such price less a concession not in excess of $ per share. The
Underwriters may allow, and such dealers may re-allow, a concession not in
excess of $ per share to certain other dealers. After the offering, the
offering price and other selling terms may be changed by the Representatives.

Prior to the offering made hereby, there has been no public market for the
Common Stock. Accordingly, the initial public offering price for the Common
Stock will be determined by negotiations among the Company and the
Representatives. Among the factors to be considered in such negotiations are the
Company's results of operations and current financial condition, estimates of
the business potential and prospects of the Company, the experience of the
Company's management, the economics of the industry in general, the general
condition of the equities market and other relevant factors. There can be no
assurance that any active trading market will develop for the Common Stock or as
to the price at which the Common Stock may trade in the public market from time
to time subsequent to the offering.

Certain persons participating in the offering may over-allot or effect
transactions that stabilize, maintain or otherwise affect the market price of
the Common Stock at levels above those which might otherwise prevail in the open
market, including by entering stabilizing bids or effecting syndicate covering
transactions. A stabilizing bid means the placing of any bid or the effecting of
any purchase, for the purpose of pegging, fixing or maintaining the price of the
Common Stock. A syndicate covering transaction means the placing of any bid on
behalf of the underwriting syndicate or the effecting of any purchase to reduce
a short position created in connection with the offering. Such transactions may
be effected on the Nasdaq National Market, in the over-the-counter market, or
otherwise. Such stabilizing, if commenced, may be discontinued at any time.

The Company has granted to the Underwriters an option, expiring 30 days from
the date of this Prospectus, to purchase up to 525,000 additional shares of
Common Stock on the same terms as set forth on the cover page of this
Prospectus, solely to cover over-allotments, if any, incurred in the sale of the
shares of Common Stock offered hereby. If the Underwriters exercise the option,
each Underwriter will

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have a firm commitment, subject to certain conditions, to purchase such number
of additional shares of Common Stock as is proportional to such Underwriter's
initial commitment to purchase shares from the Company.

The Company has agreed that during the period beginning from the date of
this Prospectus and continuing to and including the date 180 days after the date
of this Prospectus, not to offer, sell, contract to sell or otherwise dispose of
any shares of Common Stock, any securities of the Company that are substantially
similar to the shares of the Common Stock or that are convertible or
exchangeable into securities that are substantially similar to the shares of the
Common Stock (other than pursuant to the Company's employee stock option plans)
without the prior written consent of Furman Selz LLC, except for the shares of
Common Stock offered in connection with this offering. The Company has also
agreed to require, pursuant to its rights under the Stock Incentive Plan, that
each option holder not sell or otherwise transfer or dispose of any shares of
Common Stock acquired upon exercise of such holders' options without the prior
written consent of Furman Selz LLC during the same 180 day period. Amoco has
agreed that during the period beginning from the date of this Prospectus and
continuing to and including the date one year after the date of this Prospectus,
not to offer, sell, contract to sell or otherwise dispose of any shares of
Common Stock, any securities of the Company that are substantially similar to
the shares of Common Stock or that are convertible or exchangeable into Common
Stock or securities that are substantially similar to the shares of Common Stock
without the prior written consent of Furman Selz LLC.

The Company has agreed to indemnify the Underwriters against certain
liabilities, including liabilities under the Securities Act, or to contribute to
payments that the Underwriters may be required to make in respect thereof.

The Representatives have informed the Company that the Underwriters do not
intend to confirm sales to any accounts over which they exercise discretionary
authority.

The principal address of Furman Selz LLC is 230 Park Avenue, New York, New
York 10169. The principal address of Deutsche Morgan Grenfell Inc. is 31 West
52nd Street, New York, New York 10019. The principal address of EVEREN
Securities, Inc. is 77 West Wacker Drive, 31st Floor, Chicago, Illinois 60601.

LEGAL MATTERS

The validity of the shares of Common Stock offered hereby will be passed
upon for the Company by Mayer, Brown & Platt, Chicago, Illinois. Certain legal
matters relating to this offering will be passed upon for the Underwriters by
Willkie Farr & Gallagher, New York, New York.

EXPERTS

The consolidated financial statements as of December 31, 1995 and 1996 and
September 30, 1997 and for each of the three years in the period ended December
31, 1996 and for the nine months ended September 30, 1997 included in this
Prospectus have been so included in reliance on the report of Price Waterhouse
LLP, independent accountants, given on the authority of said firm as experts in
auditing and accounting.

The statements set forth in this Prospectus under the captions "Risk
Factors--Uncertain Ability to Practice Technology," "Business--Ability to
Practice Technology," "Business--Litigation" and "Business--Patents and License
Rights and Proprietary Information" have been passed upon by McCutchen, Doyle,
Brown & Enerson, San Francisco, California, patent counsel to the Company, as
experts on such matters, and are included herein based upon that review and
approval.

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AVAILABLE INFORMATION

The Company has filed with the Securities and Exchange Commission (the
"Commission") a registration statement on Form S-1 (the "Registration
Statement," which term shall include any and all amendments, exhibits, annexes
and schedules thereto) under the Securities Act with respect to the shares of
Common Stock offered hereby. This Prospectus does not contain all of the
information set forth in the Registration Statement and the exhibits and
schedules thereto. For further information with respect to the Company and such
Common Stock, reference is hereby made to such Registration Statement, which can
be inspected and copied at the public reference facilities maintained by the
Commission at 450 Fifth Street, N.W., Washington, D.C. 20549, and at the
Regional Offices of the Commission at Seven World Trade Center, New York, New
York 10048 and 500 West Madison Street, Chicago, Illinois 60661. Copies of such
material also can be obtained from the Public Reference Section of the
Commission, 450 Fifth Street, N.W., Washington, D.C. 20549 at prescribed rates.
In addition, the Registration Statement may be accessed electronically at the
Commission's site on the World Wide Web at http://www.sec.gov.

Statements contained in this Prospectus as to the contents of any contract
or other document are not necessarily complete, and in each instance reference
is made to the copy of such contract or other document filed as an exhibit to
the Registration Statement, each such statement being qualified in all respects
by such reference.

The Company is not currently subject to the informational requirements of
the Securities Exchange Act of 1934, as amended (the "Exchange Act"). As a
result of the offering of the Company's Common Stock, the Company will become
subject to the informational requirements of the Exchange Act. The Company
intends to furnish its stockholders with annual reports containing financial
statements audited by independent accountants.

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ANNEX

GLOSSARY

AMNIOCENTESIS: An invasive procedure used to test for fetal abnormalities in
which amniotic fluid (which contains fetal cells) is withdrawn by syringe and
needle from the amniotic sac surrounding the fetus.

AMNIOCYTE: A particular type of embryo cell that is contained within amniotic
fluid. Cells contained in the amniotic fluid are sloughed off from the fetus and
are representative of the genetic make-up of the fetus.

AMPLIFICATION: An increase in amount or intensity. Gene amplification refers to
an increase in the number of copies of a gene beyond the normal number. This
occurs spontaneously in many forms of cancer. Amplification also refers to the
copying of gene sequences, for example, as in PCR or Q-beta replicase
amplification, to increase the number of copies of gene sequences available for
detection.

ANEUPLOIDY: See Aneusomy.

ANEUSOMY: Having an abnormal number of chromosomes other than the normal pair
per cell. Also termed aneuploidy.

ARRAY: A matrix of DNA probes that are attached to a solid surface, where the
identity of each probe and its location on the surface is known.

BAC (BACTERIAL ARTIFICIAL CHROMOSOME): Used for molecular cloning of DNA
fragments that are approximately 100 to 200 kilobases in length.

BANDING: A technique of staining chromosomes to produce a characteristic pattern
of lateral bands across a metaphase chromosome.

BASE: Refers to the part of a nucleotide in a DNA molecule such as Adenine,
Thymine, Guanine or Cytosine, which chemically distinguishes them from one
another.

BASE PAIR (BP): Base pair refers to a complementary set of nucleotides in DNA.
Adenine (A) is always paired to thymine (T), and guanine (G) is always paired to
cytosine (C). A thousand base pairs is one kilobase (kb). The base pair is a
unit of measurement of the length of double stranded DNA sequence.

CELL: The smallest unit of living structure capable of independent existence,
composed of a membrane-enclosed mass of protoplasm and containing a nucleus.

CENTROMERE OR CENTROMERIC REGION: The constricted region usually near the center
of a chromosome consisting of highly repeated DNA sequences.

CHEMOTHERAPY: The use of drugs (such as methotrexate and adriamycin) in the
treatment or control of diseases.

CHORIONIC VILLI: Fingerlike projections extending from the vascular region of
the membrane surrounding the fetus to the uterine lining. The cells in this
tissue have the same genetic profile as that of the embryo and therefore can be
used to detect genetic defects of the embryo.

CHORIONIC VILLI SAMPLING (CVS): A procedure used to obtain a specimen of
chorionic villi for the purposes of prenatal diagnosis at 8 to 10 weeks
gestation.

CHROMOSOME: Structure in a cell on which genes are located, consisting of a
highly compacted stretch of DNA with associated proteins.

C-MYC: An oncogene found on chromosome 8 at locus 8q24. Translocation or
amplification of this oncogene may result in cancer.

COMPARATIVE GENOMIC HYBRIDIZATION (CGH): A method for analyzing DNA for
unbalanced genetic alterations. Using CGH one can observe the gains and losses
of whole chromosomes or parts of chromosomes.

CONTIG: A set of DNA clones or probes which collectively span, without gaps, a
particular gene region.

A-1
<PAGE>
CRI-DU-CHAT SYNDROME: A non-hereditary congenital disease caused by the loss of
DNA on the short arm of chromosome 5.

CYSTOSCOPY: The use of a flexible scope inserted through the urethra to examine
the bladder.

CYTOGENETICS: The study of heredity, human chromosomes and their abnormalities.

CYTOLOGY: The study of cells, their formation, structure, function and
pathology.

DENATURATION: The separation of double stranded chromosomal DNA into its
component single strands.

DIRECT LABELING: The attachment of a fluorophore directly onto a DNA probe.

DNA: An acronym for deoxyribonucleic acid, the chemical basis of heredity. DNA
contains all the information necessary for any organism to develop and function.
The four chemical building blocks of DNA are Adenine, Thymine, Cytosine and
Guanine.

DOWN SYNDROME: A non-hereditary congenital disease caused by an extra copy of
chromosome 21 (trisomy 21).

FLUORESCENCE: Visible light of various colors that is emitted by certain
fluorescent molecules when irradiated with light of a particular wavelength.

FLUORESCENCE IN SITU HYBRIDIZATION (FISH): A technique utilizing a fluorophore
labeled DNA probe to detect a particular chromosome or gene that is visualized
by fluorescence microscopy.

FLUOROPHORE: A fluorescent dye that may be attached to another molecule such as
a DNA probe which emits fluorescent light to detect the presence or location of
the molecule.

GENE: A functional unit of heredity which occupies a specific place or locus on
a chromosome.

GENE AMPLIFICATION: Increase in the normal copy number of a gene.

GENE DELETION: Loss of a copy of a gene.

GENE EXPRESSION: The process by which a gene's coded information creates the
structures present and operating in the cell. Expressed genes include those that
are transcribed into the mRNA and then translated into protein and those that
are transcribed into RNA but not translated into protein.

GENE TRANSLOCATION: Movement of a gene from its normal chromosomal location to
another location on the same or different chromosome.

GENOME: The entire complement of genetic material of an organism.

GENOMIC DNA: DNA representative of the entire genome.

GENOMIC DISEASE MANAGEMENT: An emerging field that seeks to develop new genetic
tests based on correlations between genetic abnormalities and disease.

HER-2/NEU: An oncogene associated with progression of certain cancers, e.g.,
breast and ovarian.

HYBRIDIZATION (E.G., DNA HYBRIDIZATION): The binding of complementary sequences
of DNA or RNA through specific base pairing of A:T and G:C.

IN SITU: In the natural or original position in the cell.

IN SITU HYBRIDIZATION: Hybridization occurring within an intact cell.

IN VITRO: Outside the living body.

INTERPHASE: The period of the cell cycle when the cell is not actively dividing.

IVF (IN VITRO FERTILIZATION): A process in which fertilization occurs between an
egg and sperm in an artificial environment outside of the body.

KARYOTYPE: The chromosomal characteristics (number, size and morphology) of an
individual cell, usually presented as a systematized display.

A-2
<PAGE>
KARYOTYPING: The process of generating a karyotype which is documented by the
use of a photomicrograph or a digital image generated by a genetic workstation.

METAPHASE: The stage of cell division when chromosomes are aligned at the center
of the cell prior to separation. A "metaphase spread" refers to the view of a
cell's chromosomes in the metaphase stage on a slide.

MESSENGER RNA (MRNA): An RNA that carries the genetic code for a particular gene
from the chromosome in the nucleus into the cytoplasm and acts as a template for
the formation of the protein product of the gene.

MYELOID: Cells of the blood.

NUCLEIC ACID: DNA or RNA.

NUCLEIC ACID PROBE: A specifically designed piece of DNA or RNA used to detect a
homologous target sequence of chromosomes, genes or gene sequences by nucleic
acid hybridization.

NUCLEIC ACID SEQUENCE: Refers to the order of the nucleotides in a segment of
DNA or RNA.

NUCLEOTIDE: A subunit of DNA or RNA consisting of a base (adenine, guanine,
thymine, or cytosine in DNA), a phosphate molecule and a sugar (deoxyribose)
molecule.

NUCLEUS: A cellular organelle enclosed in a definite membrane that is essential
to cell function (as reproduction and protein synthesis) and that contains
chromosomes.

OLIGONUCLEOTIDE: A synthetically developed short linear sequence of up to
approximately 40 to 50 nucleotides.

ONCOGENE: A gene that causes a cell to grow in an uncontrolled manner and is
responsible for tumor development. Mutation, over-expression, or amplification
of oncogenes in cells may cause the cell to "transform" to a cancerous state.

PAP (PAP TEST): A common test utilizing cells that are scraped from the cervix
and vagina. The cells are studied for histological and physiological changes
that may be indicative of disease after being treated with Papanicolaou stain.

PCR (POLYMERASE CHAIN REACTION): An enzymatic method of directing replication of
a segment containing a specific DNA sequence of interest, to rapidly produce
many copies of the sequence.

POINT MUTATION: A single base change of DNA sequence.

Q-BETA REPLICASE (QBR): A RNA polymerase occurring naturally in the
bacteriophage QB. Its enzymic function is to make many copies of its RNA
substrate and can be used as a sensitive method of rapidly generating an easily
detectable signal, serving as a functional alternative amplification technology.

Q-BETA REPLICASE AMPLIFICATION (QBR AMPLIFICATION): Amplification of the probe
(as opposed to the target) by Q-beta replicase provides a sensitive method of
generating a large detectable signal. QBR amplification achieves a billion-fold
increase of the probe in as little as 30 minutes without temperature cycling.

RNA (RIBONUCLEIC ACID): Any of a family of polynucleotides characterized by
their component sugar (ribose) and one of their pyrimidines (uracil). There are
three classes of RNA: messenger RNA (mRNA), ribosomal RNA (rRNA) and transfer
RNA (tRNA).

RECEPTOR: (1) A chemical group or protein molecule in a cell that has an
affinity for a specific hormone, chemical, molecule or virus or (2) a cellular
entity that acts as an intermediary between a chemical agent and a tissue in
which the interaction results in an identifiable physical response by the cells
of tissue.

TRISOMY: A chromosomal abnormality where three copies of a chromosome exist
within a cell nucleus.

A-3
<PAGE>
VYSIS, INC.
(AN INDIRECT SUBSIDIARY
OF AMOCO CORPORATION)

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

<TABLE>
<S> <C>
Report of Independent Accountants..................................................... F-2
Consolidated Balance Sheet............................................................ F-3
Consolidated Statement of Operations.................................................. F-4
Consolidated Statement of Stockholders' Equity........................................ F-5
Consolidated Statement of Cash Flows.................................................. F-6
Notes to Consolidated Financial Statements............................................ F-7
</TABLE>

F-1
<PAGE>
REPORT OF INDEPENDENT ACCOUNTANTS

To the Board of Directors and Stockholders of
Vysis, Inc.

In our opinion, the accompanying consolidated balance sheet and the related
consolidated statements of operations, of stockholders' equity and of cash flows
present fairly, in all material respects, the financial position of Vysis, Inc.
(an indirect subsidiary of Amoco Corporation) and its subsidiaries at December
31, 1995 and 1996 and September 30, 1997, and the results of their operations
and their cash flows for each of the three years in the period ended December
31, 1996 and the nine month period ended September 30, 1997, in conformity with
generally accepted accounting principles. These financial statements are the
responsibility of Vysis, Inc.'s management; our responsibility is to express an
opinion on these financial statements based on our audits. We conducted our
audits of these statements in accordance with generally accepted auditing
standards which require that we plan and perform the audit to obtain reasonable
assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements, assessing the
accounting principles used and significant estimates made by management, and
evaluating the overall financial statement presentation. We believe that our
audits provide a reasonable basis for the opinion expressed above.

PRICE WATERHOUSE LLP
Chicago, Illinois
November 21, 1997

F-2
<PAGE>
VYSIS, INC.

(AN INDIRECT SUBSIDIARY
OF AMOCO CORPORATION)

CONSOLIDATED BALANCE SHEET
(IN THOUSANDS OF DOLLARS,
EXCEPT PER SHARE AMOUNTS)

<TABLE>
<CAPTION>
PRO FORMA
STOCKHOLDERS'
DECEMBER 31, SEPTEMBER 30, EQUITY
-------------------- ------------- AT SEPTEMBER
1995 1996 1997 30,
--------- --------- ------------- 1997
(NOTE 1)
---------------
(UNAUDITED)
<S> <C> <C> <C> <C>
ASSETS
Current assets:
Cash..................................................... $ 247 $ 48 $ 294
Accounts receivable, net................................. 1,568 2,801 3,391
Inventories.............................................. 1,336 2,390 2,688
Other current assets..................................... 206 761 902
--------- --------- -------------
Total current assets................................... 3,357 6,000 7,275
Property and equipment, net................................ 13,205 5,557 4,954
Investments................................................ 715 100 100
Goodwill, net.............................................. -- 388 276
Other assets............................................... 1,890 3,070 2,488
--------- --------- -------------
Total assets........................................... $ 19,167 $ 15,115 $ 15,093
--------- --------- -------------
--------- --------- -------------
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
Accounts payable and accrued liabilities................. $ 5,632 $ 7,109 $ 7,104
Notes payable--Amoco..................................... -- 5,106 7,381
Deferred revenue......................................... 350 407 552
--------- --------- -------------
Total current liabilities.............................. 5,982 12,622 15,037
--------- --------- -------------
Commitments and contingencies (Notes 6, 10 and 12)

Stockholders' equity:
Convertible preferred stock, $0.001 par value; 10,000,000
shares authorized:
Series A; none issued and outstanding at December 31,
1995; 6,200,000 shares designated, issued and
outstanding at December 31, 1996 and September 30,
1997; none issued and outstanding pro forma............ -- 6 6 $ --
Series B; none issued and outstanding at December 31,
1995 and 1996; 553,126 designated, issued and
outstanding at September 30, 1997; none issued and
outstanding pro forma.................................. -- -- 1 --
Common stock, $0.001 par value; 35,000,000 shares
authorized; none issued and outstanding at December 31,
1995; 1,058,394 shares issued and outstanding at
December 31, 1996, 1,071,972 issued and outstanding at
September 30, 1997; 6,001,260 shares issued and
outstanding pro forma.................................. -- 1 1 6
Additional paid-in capital............................... -- 17,555 27,012 27,014
Capital contribution--Amoco.............................. 13,189 -- -- --
Deferred compensation.................................... -- (90) (259) (259)
Cumulative translation adjustment........................ (4) 16 (248) (248)
Accumulated deficit...................................... -- (14,995) (26,457) (26,457)
--------- --------- ------------- ---------------
Total stockholders' equity............................. 13,185 2,493 56 $ 56
--------- --------- ------------- ---------------
---------------
Total liabilities and stockholders' equity............. $ 19,167 $ 15,115 $ 15,093
--------- --------- -------------
--------- --------- -------------
</TABLE>

The accompanying notes are an integral part of these financial statements.

F-3
<PAGE>
VYSIS, INC.

(AN INDIRECT SUBSIDIARY
OF AMOCO CORPORATION)

CONSOLIDATED STATEMENT OF OPERATIONS
(IN THOUSANDS OF DOLLARS, EXCEPT PER SHARE AMOUNTS)

The accompanying notes are an integral part of these financial statements.

F-4
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY
(IN THOUSANDS OF DOLLARS)

<TABLE>
<CAPTION>
NINE MONTHS ENDED
YEAR ENDED DECEMBER 31, SEPTEMBER 30,
------------------------------------- ------------------
1994 1995 1996 1997
----------- ----------- ----------- ------------------
<S> <C> <C> <C> <C>
Convertible preferred stock:
Beginning balance.................................... $ -- $ -- $ -- $ 6
Recapitalization..................................... -- -- 6 --
Issuance of Series B convertible preferred stock..... -- -- -- 1
----------- ----------- ----------- ----------
Ending balance....................................... -- -- 6 7
----------- ----------- ----------- ----------
Common stock:
Beginning balance.................................... -- -- -- 1
Recapitalization..................................... -- -- 1 --
----------- ----------- ----------- ----------
Ending balance....................................... -- -- 1 1

Additional paid-in capital:
Beginning balance.................................... -- -- -- 17,555
Recapitalization..................................... -- -- 12,311 --
Income tax benefit from Amoco........................ -- -- 5,031 4,067
Deferred compensation................................ -- -- 213 277
Conversion of note payable--Amoco.................... 5,105
Exercise of stock options............................ 8
----------- ----------- ----------- ----------
Ending balance....................................... -- -- 17,555 27,012
----------- ----------- ----------- ----------
Capital contribution - Amoco:
Beginning balance.................................... 11,720 15,506 13,189 --
Net loss (pre-recapitalization)...................... (18,659) (17,701) (3,186) --
Advances from Amoco.................................. 22,445 15,384 2,315 --
Recapitalization..................................... -- -- (12,318) --
----------- ----------- ----------- ----------
Ending balance....................................... 15,506 13,189 -- --
----------- ----------- ----------- ----------
Deferred compensation:
Beginning balance.................................... -- -- -- (90)
Stock option grants.................................. -- -- (213) (277)
Amortization......................................... -- -- 123 108
----------- ----------- ----------- ----------
Ending balance....................................... -- -- (90) (259)
----------- ----------- ----------- ----------
Cumulative translation adjustment:
Beginning balance.................................... -- 4 (4) 16
Current period activity.............................. 4 (8) 20 (264)
----------- ----------- ----------- ----------
Ending balance....................................... 4 (4) 16 (248)
----------- ----------- ----------- ----------
Accumulated deficit:
Beginning balance.................................... -- -- -- (14,995)
Net loss (post-recapitalization)..................... -- -- (14,995) (11,462)
----------- ----------- ----------- ----------
Ending balance....................................... -- -- (14,995) (26,457)
----------- ----------- ----------- ----------
Total stockholders' equity............................. $ 15,510 $ 13,185 $ 2,493 $ 56
----------- ----------- ----------- ----------
----------- ----------- ----------- ----------
</TABLE>

The accompanying notes are an integral part of these financial statements.

F-5
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

CONSOLIDATED STATEMENT OF CASH FLOWS
(IN THOUSANDS OF DOLLARS)

<TABLE>
<CAPTION>
NINE MONTHS ENDED
YEAR ENDED DECEMBER 31, SEPTEMBER 30,
---------------------------------- -----------------------
1994 1995 1996 1997
---------- ---------- ---------- 1996 ----------
-----------
(UNAUDITED)
<S> <C> <C> <C> <C> <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss........................................... $ (18,659) $ (17,701) $ (18,181) $ (13,788) $ (11,462)
Reconciliation of net loss to net cash used in
operating activities:
Depreciation and amortization.................... 2,019 2,065 1,805 1,435 2,360
Loss (gain) on disposition of assets............. 11 305 (246) (32) 5
Donation of marketable securities................ -- -- 515 515 --
Stock compensation............................... -- -- 123 103 108
Changes in assets and liabilities:
Accounts receivable............................ (418) (480) (943) (169) (756)
Inventories.................................... (273) 204 (804) (1,243) (380)
Other current assets........................... 22 353 (467) 331 (176)
Accounts payable and accrued liabilities....... 1,066 3,568 770 53 (178)
Deferred revenue............................... -- 350 57 150 145
---------- ---------- ---------- ----------- ----------
Net cash used in operating activities............ (16,232) (11,336) (17,371) (12,645) (10,334)
---------- ---------- ---------- ----------- ----------
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment................ (4,234) (2,873) (509) (372) (249)
Acquisition of Techgen............................. -- -- (295) (295) --
Proceeds from sale of property and equipment....... -- -- 6,778 6,778 7
Proceeds from sale of investment................... -- -- 314 -- --
Increase in other assets........................... (521) (485) (1,548) (2,624) (629)
---------- ---------- ---------- ----------- ----------
Net cash provided by (used in) investing
activities..................................... (4,755) (3,358) 4,740 3,487 (871)
---------- ---------- ---------- ----------- ----------
CASH FLOWS FROM FINANCING ACTIVITIES:
Capital contributions--Amoco, net.................. 9,424 11,882 2,315 2,118 --
Increase in notes payable--Amoco................... -- -- 9,649 6,686 10,939
Expenses funded by Amoco........................... 11,569 3,058 452 197 509
Proceeds from exercise of stock options............ -- -- -- -- 8
---------- ---------- ---------- ----------- ----------
Net cash provided by financing activities........ 20,993 14,940 12,416 9,001 11,456
Effect of exchange rate changes on cash.............. 4 (9) 16 12 (5)
---------- ---------- ---------- ----------- ----------
Net increase (decrease) in cash...................... 10 237 (199) (145) 246
Cash at beginning of period.......................... -- 10 247 247 48
---------- ---------- ---------- ----------- ----------
Cash at end of period................................ $ 10 $ 247 $ 48 $ 102 $ 294
---------- ---------- ---------- ----------- ----------
---------- ---------- ---------- ----------- ----------
</TABLE>

The accompanying notes are an integral part of these financial statements.

F-6
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 1--ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES:

ORGANIZATION AND BUSINESS

Vysis, Inc. ("Vysis" or the "Company") was incorporated in Delaware in 1991.
The Company's principal stockholder is Amoco Technology Company ("ATC"), which
is a wholly owned subsidiary of Amoco Corporation ("Amoco"). In 1991, ATC
acquired from Genzyme its remaining interest in Gene-Trak Systems, a joint
venture focused on infectious disease diagnostics originally formed by Amoco and
Integrated Genetics in 1986, and established Gene-Trak, Inc., a Delaware
corporation, which at that time was named Gene-Trak Systems Corporation. In
March 1994, ATC contributed all of its infectious disease business related
assets and the stock of Gene-Trak, Inc. to the Company. Also, in March 1994, ATC
contributed to the Company all of its genetic disease business related assets,
including the stock of Vysis, Inc. (an Illinois corporation), which at that time
was named Imagenetics Incorporated. In January 1995, ATC contributed to the
Company all of the assets of its bioinformatics software activities. All assets
contributed by Amoco were recorded by the Company at Amoco's net book value at
the date of transfer. All references to Amoco shall mean Amoco Corporation, an
Indiana corporation, and its wholly owned subsidiary Amoco Technology Company, a
Delaware corporation.

Vysis is a genomic disease management company focused on developing and
marketing clinical products to assess the structure and function of the human
genome. The Company's DNA probe technologies provide the clinician with an
enhanced ability to manage disease by assessing the human genome at all levels,
including the ability to determine the presence, absence, number and structure
of chromosomes, individual genes, and specific base pair mutations within genes.
The Company currently markets its genomic testing products for research and
clinical use and markets its food testing products for commercial use.

BASIS OF PRESENTATION

The accompanying consolidated financial statements include those assets,
liabilities, revenues and expenses directly attributable to the Company's
operations. The Company's organization, capitalization and outstanding shares
prior to the 1996 recapitalization, as described in Note 7, are not indicative
of the Company's future structure. Consequently, the accumulated deficit, net
loss and equity contributions are reflected as a single line item "Capital
Contribution - Amoco" in the accompanying consolidated financial statements
prior to February 29, 1996.

PRINCIPLES OF CONSOLIDATION

The consolidated financial statements include the accounts of the Company
and its wholly owned subsidiaries. All significant intercompany accounts and
transactions have been eliminated.

USE OF ESTIMATES

The preparation of financial statements in conformity with generally
accepted accounting principles requires management to make estimates and
assumptions that affect certain reported amounts. Actual results may differ from
those estimates.

F-7
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 1--ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES: (CONTINUED)
INTERIM FINANCIAL INFORMATION

Interim financial information for the nine month periods ended September 30,
1996 included herein is unaudited; however, in the opinion of management, the
interim financial information includes all adjustments, consisting of only
normal recurring adjustments, necessary for a fair presentation of the results
for the interim periods. The results of operations for the nine months ended
September 30, 1997 are not necessarily indicative of the results for the entire
year.

INITIAL PUBLIC OFFERING

In October 1997, the Board of Directors authorized the Company to proceed
with an initial public offering of the Company's Common Stock (the "Offering").
In connection with the Offering, all of the Company's Convertible Preferred
Stock will automatically convert into 4,929,288 shares of Common Stock. The pro
forma effect of this conversion has been reflected on the accompanying pro forma
balance sheet assuming it had occurred at September 30, 1997 and is unaudited.

PROFITABILITY UNCERTAIN AND NEED FOR FUTURE CAPITAL

The Company has funded its operations to date primarily through capital
contributions and loans from Amoco and cash flows from operations. Amoco intends
to provide financial support to the Company through the earlier of the
completion of the Offering or December 31, 1998. In order to continue operating
and expand its business, however, the Company will need to raise additional
funds. There can be no assurance that any such additional capital will be
available to the Company, or if available, that it will be available on terms
acceptable to Vysis management. The inability of the Company to obtain
additional financing beyond 1998 would have a material adverse impact on the
Company's ability to execute its business plan.

REVENUE RECOGNITION

Product sales revenue is recognized upon shipment of products to customers.
No rights to return products exist other than under normal warranty provisions.
Grant and license fee revenue is recognized as earned pursuant to the related
agreement and is not subject to repayment. Payments received under these
agreements prior to the completion of the related work are recorded as deferred
revenue. Revenue on equipment maintenance contracts is deferred and recognized
ratably over the period of the contract, generally one year.

RESEARCH AND DEVELOPMENT EXPENDITURES

Research and development costs are expensed as incurred and include amounts
relating to grant revenues.

INVENTORIES

Inventories are stated at the lower of cost or market. Cost is determined on
the first-in, first-out method. Inventories are reassessed periodically to
determine whether any potential impairment exists.

F-8
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 1--ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES: (CONTINUED)
Provision for potentially obsolete or slow moving inventory is made based on
management's analysis of inventory levels and anticipated future sales.

CAPITALIZED SOFTWARE COSTS

Software development costs incurred subsequent to the establishment of
technological feasibility are capitalized in accordance with Statement of
Financial Accounting Standards ("SFAS") No. 86, "Accounting for the Cost of
Computer Software to be Sold, Leased, or Otherwise Marketed." Amortization of
capitalized software development costs is the greater of the amount computed
using (a) the ratio of current revenues to the total of current and anticipated
future revenues or (b) the straight-line method over the estimated economic life
of the product.

PROPERTY AND EQUIPMENT

Property and equipment are recorded at cost. Depreciation is provided on the
straight-line basis over the following expected useful lives:

Buildings and improvements 10 to 45 years

Furniture, fixtures and equipment 3 to 7 years

Leasehold improvements are depreciated over the shorter of their useful life or
lease term. Significant improvements are capitalized and repairs and maintenance
charges are expensed as incurred.

INTANGIBLE ASSETS

Intangible assets include capitalized license fees, which are carried at
cost less accumulated amortization, and goodwill. Amortization expense is
calculated on a straight-line basis over the estimated economic useful lives of
the assets, ranging from one to seventeen years. The Company periodically
reviews the recoverability of these assets based primarily upon estimated future
cash flows.

FINANCIAL INSTRUMENTS

The carrying value of accounts receivable, accounts payable and the note
payable to Amoco approximates their fair value. Financial instruments that
potentially subject the Company to concentrations of credit risk consist
principally of accounts receivable. Such credit risk is generally limited due to
the large number of organizations comprising the Company's customer base and
their dispersion across different geographic locations. The Company maintains an
allowance for potentially doubtful accounts based upon specific circumstances,
historical trends and other information.

FOREIGN CURRENCY TRANSLATION

The functional currency for the Company's foreign subsidiaries is the local
currency. Translation from the applicable foreign currency to U.S. dollars is
performed for assets and liabilities using exchange rates in effect at the
balance sheet date and for the statement of operations using the average
exchange rates in effect during the period. Gains or losses from such
translations are accumulated in a separate component

F-9
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 1--ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES: (CONTINUED)
of stockholders' equity. Gains and losses resulting from foreign currency
transactions are included in the results of operations and have not been
significant.

STOCK-BASED COMPENSATION

Effective January 1, 1996, the Company adopted the disclosure requirements
of SFAS No. 123 "Accounting for Stock-Based Compensation." As permitted, the
Company continues to recognize stock-based compensation costs under the
intrinsic value based method of accounting as prescribed by Accounting
Principles Board Opinion No. 25. The pro forma effects of applying the
provisions of SFAS No. 123 are shown in Note 8 to the consolidated financial
statements.

INCOME TAXES

Amoco has utilized the tax benefits associated with the Company's net
operating losses for the years ended December 31, 1994, 1995 and 1996 and for
the nine months ended September 30, 1997, pursuant to the terms of a tax sharing
agreement. The Company did not record any tax benefit associated with its losses
for the years ended December 31, 1994 and 1995 (see Note 2).

RECENT ACCOUNTING PRONOUNCEMENTS

PRO FORMA NET LOSS PER SHARE AND PRO FORMA SHAREHOLDERS' EQUITY

The Company's historical capital structure is not indicative of its
prospective structure given the conversion of all shares of Preferred Stock into
Common Stock concurrent with the closing of the Company's anticipated initial
public offering. Accordingly, historical net loss per common share is not
considered meaningful and has not been presented herein. The calculation of
shares used in computing pro forma net loss per share includes the effect of the
conversion of the Series A and Series B Convertible Preferred Stock into
4,525,547 and 403,741 shares, respectively, of Common Stock. These conversions
are assumed to occur concurrent with the closing of the Company's anticipated
initial public offering as if they were converted as of January 1, 1996. Common
Stock equivalent shares arising from stock options and warrants are excluded
from the calculation because their effect is antidilutive, except that Common
Stock equivalent shares arising from stock options and warrants (using the
treasury stock method and the

F-10
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 1--ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES: (CONTINUED)
anticipated initial public offering price) issued during the twelve month period
preceding the initial public offering are included in the computation of pro
forma net loss per share in accordance with SEC Staff Accounting Bulletin No.
83.

NOTE 2--RELATED PARTY TRANSACTIONS:

The Company has in the past received certain legal services, research and
development support, and administrative support from Amoco and has paid for such
services and support on an actual usage or pro rata basis. The amounts of these
costs included in the consolidated statement of operations were as follows (in
thousands):

<TABLE>
<CAPTION>
NINE MONTHS ENDED
YEAR ENDED DECEMBER 31, SEPTEMBER 30,
------------------------------- --------------------
1994 1995 1996 1996 1997
--------- --------- --------- --------- ---------
<S> <C> <C> <C> <C> <C>
Research and development......................... $ 8,441 $ 2,099 $ -- $ -- $ --
Selling, general and administrative.............. 3,128 959 304 216 142
--------- --------- --------- --------- ---------
$ 11,569 $ 3,058 $ 304 $ 216 $ 142
--------- --------- --------- --------- ---------
--------- --------- --------- --------- ---------
</TABLE>

Management of the Company believes these costs are reasonable under the
circumstances. These charges may not be indicative of the actual costs that
would have been incurred if the Company had operated independently. The Company
also received cash advances, to meet its working capital requirements, and other
capital assets from Amoco. Through December 31, 1995, all such amounts were
recorded as contributed capital and aggregated $22,445,000 and $15,384,000 in
1994 and 1995, respectively. During 1996, such amounts consisted of contributed
capital of $2,315,000 and advances of $10,137,000 under a note payable to Amoco.
During the nine months ended September 30, 1997 such advances aggregated
$11,448,000 under a note payable to Amoco.

The Company has entered into a tax sharing agreement with Amoco effective
January 1, 1996 which provides for a capital contribution to the Company in an
amount approximating the tax effect of including the Company's results of
operations in Amoco's consolidated federal income tax return. Under this
agreement, $5,031,000 and $4,067,000 were recorded as contributed capital and a
related reduction of the note payable to Amoco during 1996 and the nine months
ended September 30, 1997, respectively. Under the terms of the tax sharing
agreement, the Company will continue to receive during the remainder of 1997 and
beyond a capital contribution approximating the amounts realized by Amoco, which
relate to deductions or losses to be generated by the Company, for as long as
the Company is included in Amoco's consolidated federal tax return. Pursuant to
the terms of the agreement, state income taxes have not been material.

The Company participates in Amoco's centralized cash management program. As
a result, excess cash receipts are transferred to a centralized cash account
maintained by Amoco.

The note payable to Amoco of $5,106,000 at December 31, 1996 included
accrued interest of $148,000. The note bore interest at 7.5% and was converted
into 553,126 shares of Series B Preferred Stock in September 1997 (see Note 7).
The note payable to Amoco of $7,381,000 at September 30, 1997, includes accrued
interest expense of $367,000, bears interest at 7.5% and is due on the earlier
of the date the Company completes the Offering or December 31, 1998.

F-11
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 3--COMPOSITION OF BALANCE SHEET COMPONENTS:

Accounts receivable consisted of the following (in thousands):

<TABLE>
<CAPTION>
DECEMBER 31, SEPTEMBER 30,
-------------------- -------------
1995 1996 1997
--------- --------- -------------
<S> <C> <C> <C>
Accounts receivable........................................ $ 1,788 $ 2,957 $ 3,573
Less: allowance for doubtful accounts...................... (220) (156) (182)
--------- --------- ------
$ 1,568 $ 2,801 $ 3,391
--------- --------- ------
--------- --------- ------
</TABLE>

Inventories consisted of the following (in thousands):

<TABLE>
<CAPTION>
DECEMBER 31, SEPTEMBER 30,
-------------------- -------------
1995 1996 1997
--------- --------- -------------
<S> <C> <C> <C>
Raw materials and supplies................................. $ 588 $ 997 $ 1,046
Finished goods............................................. 748 1,393 1,642
--------- --------- ------
$ 1,336 $ 2,390 $ 2,688
--------- --------- ------
--------- --------- ------
</TABLE>

Property and equipment consisted of the following (in thousands):

<TABLE>
<CAPTION>
DECEMBER 31, SEPTEMBER 30,
-------------------- -------------
1995 1996 1997
--------- --------- -------------
<S> <C> <C> <C>
Land..................................................... $ 1,320 $ -- $ --
Buildings and improvements............................... 6,516 2,382 2,382
Furniture, fixtures and equipment........................ 11,005 8,191 8,663
--------- --------- ------
18,841 10,573 11,045
Less: accumulated depreciation........................... (5,636) (5,016) (6,091)
--------- --------- ------
$ 13,205 $ 5,557 $ 4,954
--------- --------- ------
--------- --------- ------
</TABLE>

F-12
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 3--COMPOSITION OF BALANCE SHEET COMPONENTS: (CONTINUED)
Other assets consisted of the following (in thousands):

<TABLE>
<CAPTION>
DECEMBER 31, SEPTEMBER 30,
-------------------- -------------
1995 1996 1997
--------- --------- -------------
<S> <C> <C> <C>
License fees (net of accumulated amortization of $144, $509
and $1,369 in 1995, 1996 and 1997, respectively).......... $ 1,385 $ 2,535 $ 1,582
Prepaid royalties.......................................... 402 -- --
Software development costs (net of accumulated amortization
of $0, $40 and $112 in 1995, 1996 and 1997,
respectively)............................................. 97 535 906
Other...................................................... 6 -- --
--------- --------- ------
1,890 3,070 2,488
--------- --------- ------
--------- --------- ------
</TABLE>

Accounts payable and accrued liabilities consisted of the following (in
thousands):

<TABLE>
<CAPTION>
DECEMBER 31, SEPTEMBER 30,
-------------------- -------------
1995 1996 1997
--------- --------- -------------
<S> <C> <C> <C>
Trade accounts payable..................................... $ 3,523 $ 3,546 $ 3,218
Accrued rent............................................... 828 1,141 1,119
Employee related costs..................................... 577 743 585
Other taxes payable........................................ 189 423 400
Accrued legal costs........................................ 75 504 521
Other...................................................... 440 752 1,261
--------- --------- ------
$ 5,632 $ 7,109 $ 7,104
--------- --------- ------
--------- --------- ------
</TABLE>

NOTE 4--INVESTMENTS:

CANJI, INC.

The Company entered into a license agreement with Canji, Inc. ("Canji") in
1994, whereby the Company was granted an exclusive license to use certain
patented technology. In exchange for the license, the Company paid $600,000 in
cash and surrendered preferred stock of Canji aggregating approximately
$900,000. Accumulated amortization related to the license aggregated $132,000
and $221,000 at December 31, 1995 and 1996, respectively, and $287,000 at
September 30, 1997. The agreement provides that the Company will pay Canji
royalties of up to 5 percent of net sales of the licensed products.
Additionally, at December 31, 1995, the Company held preferred stock in Canji, a
private company, which was carried at cost and approximated $515,000. In 1996,
Canji was acquired by Schering-Plough Corporation and the Company's investment
in Canji was exchanged for shares of Schering-Plough. During September 1996, the
Company donated its investment in Schering-Plough to a not-for-profit
organization affiliated with Amoco.

F-13
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 4--INVESTMENTS: (CONTINUED)
GENOME SYSTEMS, INC.

In 1994, the Company acquired 1,400 shares of preferred stock in Genome
Systems, Inc. for cash consideration of $200,000. In 1996, Genome Systems, Inc.
was acquired by Incyte Pharmaceuticals, Inc. ("Incyte") and the Company's
investment was exchanged for restricted common stock of Incyte, a publicly held
company. During 1996, a portion of this investment with a cost of $100,000 was
sold and a gain of $214,000 was included in the Company's results of operations.
The remaining investment balance consists of Incyte restricted common stock and
is therefore recorded at cost of $100,000 at December 31, 1996 and September 30,
1997.

NOTE 5--INCOME TAXES:

The approximate income tax effect of each temporary difference giving rise
to deferred tax assets and liabilities is as follows (in thousands):

<TABLE>
<CAPTION>
DECEMBER 31, SEPTEMBER 30,
-------------------- -------------
1995 1996 1997
--------- --------- -------------
<S> <C> <C> <C>
Deferred tax assets:
Patents and purchased software........................... $ 274 $ 255 $ 362
Deferred rent............................................ 318 457 448
Foreign net operating loss carryforwards................. 200 374 584
Accrued vacation......................................... 117 130 122
Bad debt accrual......................................... 88 62 71
Other.................................................... 40 158 524
--------- --------- -------------

Total deferred tax assets.................................. 1,037 1,436 2,111

Valuation allowance........................................ (997) (790) (1,582)
--------- --------- -------------

Net deferred tax assets.................................... 40 646 529

Deferred tax liabilities:
Software development costs and license fees.............. (40) (646) (529)
--------- --------- -------------

Net deferred tax assets.................................... $ -- $ -- $ --
--------- --------- -------------
--------- --------- -------------
</TABLE>

The Company had foreign net operating loss carryforwards of $1,459,000 at
September 30, 1997 of which approximately $546,000 will expire at varying dates
through 2001 and the remainder of which may be carried forward indefinitely.

F-14
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 5--INCOME TAXES: (CONTINUED)
A full valuation allowance has been provided for all deferred tax assets
(net of liabilities) as management does not consider realization of such amounts
more likely than not. On an unaudited pro forma separate income tax return
basis, assuming the Company was not included in the consolidated income tax
returns of Amoco, no tax provision or benefit would have been recorded in the
consolidated financial statements due to the ongoing losses of the Company.

NOTE 6--DEVELOPMENT AND LICENSE AGREEMENTS:

The Company has entered into various license agreements pursuant to which it
has been granted exclusive and non-exclusive licenses to certain patented
technologies. The agreements require the Company to pay royalties ranging from
0.5 to 8.0 percent on net sales of specified products, with certain agreements
requiring minimum royalties due each year. As additional consideration for
certain of the licenses, the Company is obligated to fund certain research of
the licensors. Future minimum amounts due for such licenses, minimum royalties
and research funding are as follows (in thousands):

<TABLE>
<CAPTION>
YEAR ENDING
DECEMBER 31,
- -------------------------------------------------------------------------------------
<S> <C>
1997 (remaining three months)........................................................ $ --
1998................................................................................. 645
1999................................................................................. 1,835
2000................................................................................. 1,800
2001................................................................................. 600
2002................................................................................. 300
Thereafter........................................................................... --
---------
$ 5,180
---------
---------
</TABLE>

NOTE 7--RECAPITALIZATION:

On February 29, 1996, pursuant to a recapitalization, the Company issued
6,200,000 shares of its Series A Convertible Preferred Stock, par value $0.001
per share, and 1,058,394 shares of its Common Stock, par value $0.001 per share,
to Amoco as consideration for the cumulative investment by Amoco in the Company,
which was $12,318,000. The investment by Amoco in the Company included assets
contributed by Amoco which were recorded at Amoco's net book value at the date
of transfer. In connection with the recapitalization, $6,000 and $1,000 was
assigned to the par value of the Series A Convertible Preferred Stock and Common
Stock, respectively, while the remaining $12,311,000 was credited to additional
paid-in capital.

In September 1997, the Company converted $5,106,000 of the note payable due
to Amoco into 553,126 shares of its Series B Convertible Preferred Stock, par
value $0.001 per share.

The holder of Series A and Series B Convertible Preferred Stock is entitled
to receive cumulative dividends at an annual rate of 6 percent of the Series A
and Series B liquidation value (initially $8.0645

F-15
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 7--RECAPITALIZATION: (CONTINUED)
and $9.23 per share, respectively), when and if declared by the Board of
Directors. In the event of a liquidation, the holder of the Series A and Series
B Convertible Preferred Stock shall receive the sum of $8.0645 and $9.23 per
share, respectively, and any declared but unpaid dividends. Additionally, the
holder of the Series A and Series B Convertible Preferred Stock is entitled to
share in any dividends paid on Common Stock.

The holder of the Series A and Series B Convertible Preferred Stock is
entitled to vote together with the holders of Common Stock, as a single class in
all matters. The Series A and Series B holder is entitled to votes equal to the
number of common shares into which such holder's shares are convertible. Each
share of Series A and Series B Convertible Preferred Stock is convertible, at
any time at the option of the holder, into .73 share of Common Stock. Each share
of Series A and Series B Convertible Preferred Stock shall automatically convert
into .73 share of Common Stock upon closing of an initial public offering of the
Company's Common Stock resulting in aggregate net proceeds of not less than
$10,000,000. In the event of any one or more third party equity investments,
prior to the closing of an initial public offering, the Series A and Series B
Convertible Preferred Stock is subject to anti-dilution adjustments. The Company
has reserved an adequate number of its Common Stock to provide for the
conversion of the Series A and Series B shares.

NOTE 8--EMPLOYEE BENEFIT PLANS:

In February 1996, the Company adopted the 1996 Stock Incentive Plan (the
"1996 Plan"). A total of 985,402 shares of Common Stock have been authorized for
issuance under the 1996 Plan, subject to anti-dilution and other adjustments. In
general, under the 1996 Plan, incentive or nonqualified stock options may be
granted at a price not less than 100 percent of the estimated fair value of the
Common Stock on the date of grant, as determined by the Compensation Committee
of the Board of Directors. Options generally vest over 4 years and expire within
10 years from the date of grant.

F-16
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 8--EMPLOYEE BENEFIT PLANS: (CONTINUED)
Option activity under the 1996 Plan is summarized below:

<TABLE>
<CAPTION>
WEIGHTED
NUMBER OF AVERAGE
SHARES PRICE
--------- -----------
<S> <C> <C>
Granted................................................ 878,994 $ 0.58
Exercised.............................................. -- --
Surrendered or terminated.............................. 21,642 $ 0.60
---------
Balance at December 31, 1996........................... 857,352 $ 0.58

Granted................................................ 162,007 $ 3.59
Exercised.............................................. 13,578 $ 0.53
Surrendered or terminated.............................. 47,812 $ 0.57
---------
Balance at September 30, 1997.......................... 957,969 $ 1.08

Options exercisable at September 30, 1997................ 355,408 $ 0.56
Options available for future grant at September 30,
1997.................................................... 13,855

Weighted-average fair value of options granted during the
year ended December 31, 1996............................ $ 0.34
Weighted-average fair value of options granted during the
nine months ended September 30, 1997.................... $ 2.69
Weighted-average fair value of options granted below
estimated fair value for the nine months ended September
30, 1997................................................ $ 3.54
</TABLE>

During 1996, the Company issued options to consultants to purchase 44,162
shares of Common Stock at an exercise price of $0.53 per share, exercisable
through 2006. The Company recorded deferred compensation of $213,000 in
connection with these options, based upon the difference between the estimated
fair value of the services received and the exercise price of the options
granted. The Company recognized $123,000 as stock compensation expense during
the year ended December 31, 1996.

During the nine months ended September 30, 1997, the Company issued options
to employees to purchase 78,249 shares of Common Stock at an exercise price of
$2.74 per share, exercisable through 2007. The Company recorded deferred
compensation of $277,000 in connection with these options based upon differences
between the estimated fair value of the underlying stock and the exercise price
of the related options. The Company recognized $108,000 as stock compensation
expense during the nine months ended September 30, 1997.

F-17
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 8--EMPLOYEE BENEFIT PLANS: (CONTINUED)
The following summarizes information about stock options outstanding at
September 30, 1997:

<TABLE>
<CAPTION>
OPTIONS OUTSTANDING
----------------------------
WEIGHTED
AVERAGE OPTIONS EXERCISABLE
REMAINING ------------------------------
RANGE OF NUMBER CONTRACTUAL WEIGHTED AVERAGE NUMBER
EXERCISE PRICES OUTSTANDING LIFE EXERCISE PRICE EXERCISABLE
- ----------------- ----------- --------------- ----------------- -----------
<S> <C> <C> <C> <C>
$0.53 758,117 8.5 $ 0.53 342,850
1.34 38,577 8.8 1.34 12,558
2.74 127,698 9.7 2.74 --
6.85 33,577 9.9 6.85 --
----------- -----------
957,969 355,408
----------- -----------
----------- -----------
</TABLE>

The fair value of each option was estimated on the date of grant using the
Black-Scholes option pricing model. The principal determinants of option pricing
are: the estimated fair value of the Company's Common Stock at the date of
grant, expected volatility, risk-free interest rate, expected option lives and
dividend yields. Weighted average assumptions employed by the Company were as
follows:

<TABLE>
<CAPTION>
NINE MONTHS
YEAR ENDED ENDED
DECEMBER 31, SEPTEMBER 30,
1996 1997
--------------- -------------
<S> <C> <C>
Expected volatility............................................. 50.3% 47.5%
Risk free interest rate......................................... 6.2% 6.4%
Expected option life (years).................................... 7 7
Dividend yield.................................................. 0 0
</TABLE>

The Company applies Accounting Principles Board Opinion No. 25 in accounting
for its fixed stock option plan and, accordingly, has not recognized
compensation cost in the accompanying consolidated statement of operations for
options granted and exercisable at their estimated fair value on the grant date.
Had compensation cost been recognized based on fair value as of the grant dates
as defined in SFAS No. 123, the Company's net loss would have increased by
approximately $57,000 and $70,000, or $0.01 and $0.01 per share pro forma, for
the year ended December 31, 1996 and for the nine months ended September 30,
1997, respectively.

The Company also maintains the Vysis, Inc. Savings and Investment Plan (the
"Savings Plan"), as amended, which allows for participant contributions pursuant
to Section 401(k) of the Internal Revenue Code. Substantially all the Company's
U.S. employees are eligible to participate in the Savings Plan and may
contribute up to 17% of their eligible compensation to the Savings Plan. The
Company made contributions to the Savings Plan of $176,000, $210,000, $164,000
and $138,000 in 1994, 1995, 1996 and the nine months ended September 30, 1997,
respectively.

F-18
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 9--SEGMENT AND GEOGRAPHIC INFORMATION:

The Company operates in one business segment. Substantially all revenues
result from the sale of genomic testing products and related instrumentation and
the receipt of grant and other revenue. All significant intercompany revenues
and expenses are eliminated in the presentation of revenues and net loss.
Certain geographic information is as follows (in thousands):
<TABLE>
<CAPTION>
NINE MONTHS
YEAR ENDED DECEMBER 31, ENDED SEPTEMBER
---------------------------------- 30,
1994 1995 1996 1997
---------- ---------- ---------- ----------------
<S> <C> <C> <C> <C>
Revenues:
United States........................... $ 4,716 $ 5,488 $ 8,655 $ 7,525
Europe.................................. 687 1,729 4,583 4,700
---------- ---------- ---------- --------
Total............................... $ 5,403 $ 7,217 $ 13,238 $ 12,225
---------- ---------- ---------- --------
---------- ---------- ---------- --------

Net (loss) income:
United States........................... $ (18,076) $ (17,334) $ (18,094) $ (11,641)
Europe.................................. (583) (367) (87) 179
---------- ---------- ---------- --------
Total............................... $ (18,659) $ (17,701) $ (18,181) $ (11,462)
---------- ---------- ---------- --------
---------- ---------- ---------- --------

DECEMBER 31,
---------------------------------- SEPTEMBER 30,
1994 1995 1996 1997
---------- ---------- ---------- ----------------
<S> <C> <C> <C> <C>
Assets:
United States........................... $ 16,853 $ 17,155 $ 12,166 $ 11,704
Europe.................................. 721 2,012 2,949 3,389
---------- ---------- ---------- --------
Total............................... $ 17,574 $ 19,167 $ 15,115 $ 15,093
---------- ---------- ---------- --------
---------- ---------- ---------- --------
</TABLE>

Export sales from U.S. operations amounted to approximately $353,000,
$547,000 and $694,000 for the years ended December 31, 1994, 1995 and 1996,
respectively, and $928,000 for the nine months ended September 30, 1997, and
consisted of sales principally to customers in the Far East. There were no sales
to individual customers that exceeded 10 percent of total revenues for any
period presented.

NOTE 10--LEASE OBLIGATIONS:

The Company operates in leased facilities and also leases certain
manufacturing and other equipment. These leases generally require the Company to
pay taxes, maintenance, insurance and certain other operating costs of the
leased property. Most of the Company's leases contain renewal clauses.

F-19
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 10--LEASE OBLIGATIONS: (CONTINUED)
Future minimum lease payments under non-cancelable operating leases are as
follows (in thousands):

<TABLE>
<CAPTION>
YEAR ENDING
DECEMBER 31,
- -------------------------------------------------------------------------------------
<S> <C>
1997 (remaining three months)........................................................ $ 175
1998................................................................................. 748
1999................................................................................. 570
2000................................................................................. 521
2001................................................................................. 523
2002................................................................................. 679
Thereafter........................................................................... 1,301
---------
$ 4,517
---------
---------
</TABLE>

Rental expense totaled $140,000, $695,000 and $606,000 in 1994, 1995 and
1996, respectively and $462,000 for the nine months ended September 30, 1997.

NOTE 11--ACQUISITION:

On April 3, 1996, the Company acquired all of the outstanding common stock
of TechGen International Sarl ("TechGen") for $295,000. TechGen is a French
distributor of chemical, biological, health and hygiene products and equipment.
The acquisition has been accounted for under the purchase method of accounting.
Accordingly, the cash paid of $295,000 and liabilities assumed of $711,000 were
allocated to the tangible assets acquired. The excess of the purchase price over
the estimated fair value of net assets acquired of $457,000 has been assigned to
goodwill and is being amortized using the straight-line method over a five year
period.

The following unaudited pro forma financial information presents the
combined results of operations of the Company and TechGen as if the acquisition
had occurred at the beginning of each fiscal year. The pro forma information is
based on historical results of operations and does not necessarily reflect the
actual results that would have occurred, nor is it necessarily indicative of
future results of operations of the combined enterprises (in thousands):

<TABLE>
<CAPTION>
YEAR ENDED DECEMBER
31,
----------------------
1995 1996
---------- ----------
<S> <C> <C>
Revenues.............................................................. $ 8,549 $ 13,285
Net loss.............................................................. $ (17,796) $ (18,230)
</TABLE>

NOTE 12--COMMITMENTS AND CONTINGENCIES:

The Company is an exclusive licensee of certain technology. The Company and
the licensor of the technology are plaintiffs in a patent infringement suit
filed in September 1995 against one of the Company's competitors. The Company
and the licensor share the legal costs of this matter equally. In

F-20
<PAGE>
VYSIS, INC.
(An indirect subsidiary
of Amoco Corporation)

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(INFORMATION FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1996 IS UNAUDITED)

NOTE 12--COMMITMENTS AND CONTINGENCIES: (CONTINUED)
August 1997, the court ruled in favor of the Company and its licensor in several
aspects of this matter. The trial of the remaining issues has been scheduled for
April 1998. An unfavorable outcome for the Company is considered neither
probable nor remote by management. The Company does not believe that loss of
this lawsuit would have a material adverse impact on the results of operations
or the Company's financial position as set forth in the accompanying
consolidated financial statements.

The Company and Amoco are defendants in a law suit pending in the U.S.
District Court in California alleging infringement of certain patents. The suit
has been stayed pending the outcome of another suit brought against the
plaintiff challenging the plaintiff's claim to sole ownership to the patents at
issue in the first lawsuit. Pursuant to a separate agreement between Amoco and
the plaintiff in the latter lawsuit (the "Plaintiff"), the Company reimburses
the legal costs incurred by the Plaintiff in that suit. In return, the Company
receives contingent rights to acquire an exclusive license with right to
sublicense under such rights as the Plaintiff may obtain in the patents. The
Company has agreed with the Plaintiff to grant sub-licenses at commercially fair
and reasonable terms should it acquire the exclusive license. The trial in the
latter case has been scheduled for December 1997. Although the Company believes
that it has meritorious defenses in the first suit, there can be no assurance
that the Company will ultimately prevail. An unfavorable outcome for the Company
is considered neither probable nor remote by management. An estimate of a
possible loss or range of a possible loss cannot currently be made. However, an
adverse determination against the Company, which may include a finding of
willful infringement and the awarding of plaintiff's attorney's fees, could have
a material adverse effect on the Company's financial position and results of
operations.

In October 1997, the Company entered into an Asset Puchase Agreement (the
"Agreement") to purchase certain patents and other intellectual property. The
Agreement calls for Vysis to pay the seller $250,000 in cash and issue 80,291
shares of its Common Stock concurrent with the closing of the transaction, which
is expected to occur in January 1998.

NOTE 13--SUPPLEMENTAL CASH FLOW INFORMATION:

Amoco contributed property and equipment aggregating $532,000, $444,000 and
$36,000 to the Company in 1994, 1995 and 1996, respectively, and did not make
any such contributions during the nine months ended September 30, 1997 and
$920,000 of other assets in 1994. These amounts were reflected by the Company as
a capital contribution from Amoco and recorded at Amoco's net book value.

NOTE 14--STOCK SPLIT

On November 21, 1997 the Company effected a 1 for 1.37 reverse stock split
of its Common Stock. All share and per share amounts in the consolidated
financial statements and notes thereto have been adjusted retroactively to
reflect this stock split.

F-21
<PAGE>
INSIDE BACK COVER

(GRAPHICS)

A collage of eight color photographs representing a variety of the Company's
products and entitled "Current Products for Genomic Disease Management." The
first photograph in the upper left-hand corner is a snapshot of three of the
Company's clinical products and has the caption, "CEP-Registered Trademark- 8,
CEP 12 and CEP X/Y Kits for the assessment of leukemia and myeloid disorders."
The photograph in the upper right-hand corner is an image of a tissue section
with cells containing multiple colored spots (signals) and has the caption
"Breast tumor section hybridized with LSI-Registered Trademark- HER-2/neu and
CEP 17 control probes. Multiple pink fluorescent signals indicate amplification
of the HER-2/neu gene (currently in clinical trials).**"

In the center left of the page is a pair of photographs each showing a cell
containing multiple colored spots (signals) and has the caption "TriGen-TM-
Assay. Fluorescence images demonstrating hybridization of the CEP X/Y and LSI 21
probes on uncultured amniocytes. The cell on the left is normal for sex
chromosome X (green signal) and Y (pink signal). The cell on the right
demonstrates three copies of chromosome 21 (pink signal), indicating Down
syndrome (not available for sale in the United States)."

In the center right of the page is a pair of photographs each showing a cell
containing multiple colored spots (signals) and has the caption "AnueVysion-TM-.
Fluorescence images demonstrating hybridization of CEP 18, X and Y, and LSI 13
and 21 probes on uncultured amniocytes. The cell on the left shows three copies
of chromosome 18 (aqua signal) and normal copies of chromosome X (green signal)
and Y (pink signal). The cell on the right is normal for chromosomes 13 (green
signal) and 21 (pink signal)."

In the lower left-hand corner of the page is a photograph of a computer
screen from one of the Company's software products and has the caption "Quips
CGH Software showing color karyotype of metaphase cells (marketed on a Research
Use Only basis)." The photograph in the lower right-hand corner is a snapshot of
the Company's HYBrite system and is captioned "HYBrite-TM- semi-automatic system
for IN SITU hybridization."

The Company's logo and the words "Managing Disease With Molecular
Techniques" are placed at the bottom center of the page.

- ------------------------

**Diagnostic use is subject to FDA and other applicable regulatory approvals,
which have not yet been applied for or received.

<PAGE>
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

NO DEALER, SALESPERSON OR OTHER PERSON HAS BEEN AUTHORIZED TO GIVE ANY
INFORMATION OR TO MAKE ANY REPRESENTATIONS OTHER THAN THOSE CONTAINED IN THIS
PROSPECTUS, AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATIONS MUST NOT
BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE COMPANY OR THE UNDERWRITERS.
THIS PROSPECTUS DOES NOT CONSTITUTE AN OFFER TO SELL OR THE SOLICITATION OF AN
OFFER TO BUY ANY SECURITIES OTHER THAN THE SECURITIES TO WHICH IT RELATES OR ANY
OFFER TO SELL OR THE SOLICITATION OF AN OFFER TO BUY SUCH SECURITIES IN ANY
CIRCUMSTANCES IN WHICH SUCH OFFER OR SOLICITATION IS UNLAWFUL. NEITHER THE
DELIVERY OF THIS PROSPECTUS NOR ANY OFFER OR SALE MADE HEREUNDER SHALL, UNDER
ANY CIRCUMSTANCES, CREATE AN IMPLICATION THAT THERE HAS BEEN NO CHANGE IN THE
AFFAIRS OF THE COMPANY SINCE THE DATE HEREOF OR THAT THE INFORMATION HEREIN IS
CORRECT AS OF ANY TIME SUBSEQUENT TO THE DATE HEREOF.
------------------------

TABLE OF CONTENTS

<TABLE>
<CAPTION>
PAGE
----
<S> <C>
Prospectus Summary........................................................ 3
Risk Factors.............................................................. 8
The Company............................................................... 18
Use of Proceeds........................................................... 18
Dividend Policy........................................................... 18
Capitalization............................................................ 19
Dilution.................................................................. 20
Selected Financial Information............................................ 21
Management's Discussion and Analysis of Financial Condition and Results of
Operations.............................................................. 23
Business.................................................................. 27
Management................................................................ 59
Principal Stockholder and Securities Ownership of Management.............. 65
Certain Transactions...................................................... 67
Description of Capital Stock.............................................. 68
Shares Eligible for Future Sale........................................... 71
Underwriting.............................................................. 73
Legal Matters............................................................. 74
Experts................................................................... 74
Available Information..................................................... 75
Glossary.................................................................. A-1
Financial Statements...................................................... F-1
</TABLE>

UNTIL , 1998 (25 DAYS AFTER THE DATE OF THIS PROSPECTUS), ALL DEALERS
EFFECTING TRANSACTIONS IN THE COMMON STOCK, WHETHER OR NOT PARTICIPATING IN THIS
DISTRIBUTION, MAY BE REQUIRED TO DELIVER A PROSPECTUS. THIS IS IN ADDITION TO
THE OBLIGATION OF DEALERS TO DELIVER A PROSPECTUS WHEN ACTING AS UNDERWRITERS
AND WITH RESPECT TO THEIR UNSOLD ALLOTMENTS OR SUBSCRIPTIONS.

3,500,000 SHARES

[LOGO]

COMMON STOCK
------------------

PROSPECTUS

------------------

FURMAN SELZ
DEUTSCHE MORGAN GRENFELL
EVEREN SECURITIES, INC.

, 1998

- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
INFORMATION NOT REQUIRED IN THE PROSPECTUS

ITEM 13. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION

Expenses of the Registrant in connection with the issuance and distribution
of the securities being registered, other than underwriting discounts and
commissions, are as set forth below. All expenses listed below are estimates,
except for the Commission, NASD and Nasdaq fees.

<TABLE>
<S> <C>
Securities and Exchange Commission Registration Fee......................... $ 18,296
NASD Filing Fee............................................................. 6,538
Nasdaq Filing Fee........................................................... 41,000
Blue Sky Fees and Expenses (including attorneys' fees)...................... 10,000
Printing and Engraving Expenses............................................. 415,000
Legal Fees and Expenses..................................................... 276,000
Accounting Fees and Expenses................................................ 375,000
Transfer Agent and Registrar Fees and Expenses.............................. 11,000
Miscellaneous............................................................... 47,166
---------
Total................................................................... $1,200,000
---------
---------
</TABLE>

- ------------------------

* To be filed by amendment.

ITEM 14. INDEMNIFICATION OF OFFICERS AND DIRECTORS

Section 145 of the Delaware General Corporation Law authorizes
indemnification of directors and officers of the Company; allows the advancement
of costs of defending against litigation; and permits companies incorporated in
Delaware to purchase insurance on behalf of directors and officers against
liabilities whether or not in the circumstances such companies would have the
power to indemnify against such liabilities under the provisions of the statute.

The Company's Certificate of incorporation provides for indemnification of
the Company's officers and directors to the fullest extent permitted by Section
145 of the Delaware General Corporation Law. The Company intends to obtain
directors and officers insurance covering its executive officers and directors.

ITEM 15. RECENT SALES OF UNREGISTERED SECURITIES

On February 29, 1996, in connection with the reorganization of the Company,
each share of Common Stock, par value $1.00 per share, of the Company was
converted into 14,356.43564 shares of Common Stock, par value $0.001 per share
of the Company and 61,386.13861 shares of Series A Preferred Stock, par value
$0.001 per share of the Company. All such shares (which totaled 1,450,000 shares
of Common Stock and 6,200,000 shares of Series A Preferred Stock) were issued to
Amoco Technology Company ("ATC"), the Company's principal stockholder, in
reliance upon the exemption contained in Section 3(a)(9) of the Securities Act.

On March 1, 1996, the Company granted an option to purchase 36,497 shares of
Common Stock at $0.53 per share to Colin Grace, a consultant to the Company.
Such option was granted in reliance upon Rule 701 under the Securities Act as
consideration for bona fide consulting services provided by Mr. Grace.

On April 30, 1996, the Company granted an option to purchase 1,095 shares of
Common Stock at $0.53 per share to each of the following members of its
scientific advisory board: Kurt Hirschhorn, M.D., Fred R. Kramer, Ph.D., David
H. Ledbetter, Ph.D., Kenneth L. Melmon, M.D., Dan Pinkel, Ph.D., Hans J. Tanke,
Ph.D., and Stephen T. Warren, Ph.D. (collectively, the "SAB Members"). Each
option was granted

II-1
<PAGE>
in reliance upon Rule 701 under the Securities Act as consideration for bona
fide advisory services provided by each such SAB Member.

On February 28, 1997, the Company granted an option to purchase 1,095 shares
of Common Stock at $2.74 per share to each SAB Member. Each option was granted
in reliance upon Rule 701 under the Securities Act as consideration for bona
fide advisory services provided by each such SAB Member.

On September 17, 1997, the Company issued 553,126 shares of Series B
Preferred Stock to ATC, the Company's principal stockholder, in reliance upon
the exemption contained in Section 4(2) of the Securities Act. The shares of
Series B Preferred Stock were issued in settlement of a $5,106,000 intercompany
balance between the Company and ATC.

On September 30, 1997, the Company issued an aggregate of 13,578 shares of
Common Stock to five individuals upon exercise of employee stock options held by
them, in reliance upon Rule 701 under the Securities Act. The aggregate exercise
price of such options was $7,255.

On October 15, 1997, the Company agreed to issue an aggregate of 80,291
shares of Common Stock to Aprogenex, Inc., a corporation engaged in the
development of diagnostic test systems, as partial consideration for certain
patents and other intellectual property rights of such corporation. The shares
are to be issued in reliance upon the exemption contained in Section 4(2) of the
Securities Act.

All of the share amounts in this Item 15 have been adjusted to reflect the
Company's 1-for-1.37 reverse stock split effected November 21, 1997.

ITEM 16. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

(a) Exhibit Index

3.1.1* Certificate of Incorporation of Vysis, Inc. (formerly Framingham Development Company) filed April 18,
1991.

3.1.2* Certificate of Amendment of Certificate of Incorporation filed March 30, 1994.

3.1.3* Certificate of Merger filed February 1, 1996.

3.1.4* Certificate of Amendment of Certificate of Incorporation filed February 29, 1996.

3.1.5* Certificate of Correction of Certificate of Amendment filed July 22, 1996.

3.1.6* Certificate of Amendment of Certificate of Incorporation filed September 16, 1997.

3.1.7* Certificate of Designations of Series B Preferred Stock, filed September 17, 1997.

3.1.8* Certificate of Amendment of Certificate of Incorporation filed November 21, 1997.

3.2 Bylaws of Vysis, Inc.

4.1* Form of Common Stock Certificate.

5.1* Opinion of Mayer, Brown & Platt.

10.1* Vysis, Inc. 1996 Stock Incentive Plan.

10.2* Industrial Building Lease between American National Bank and Trust Company of Chicago and Vysis, Inc.
dated November 29, 1994.

10.3* License Agreement for Chromosome Analysis Technology with Chromosome-Specific Probes between ATC and
The Regents of The University of California dated August 15, 1989, as amended October 6, 1989; July 1,
1991; April 15, 1992; June 1, 1994; June 6, 1994; June 28, 1994; July 1, 1994; September 1, 1994.
</TABLE>

II-2
<PAGE>

<TABLE>
<CAPTION>
EXHIBIT
NUMBER DESCRIPTION OF DOCUMENT
- ---------- ------------------------------------------------------------------------------------------------------
<S> <C>
10.4* Exclusive License Agreement between The Regents of The University of California and Imagenetics for
Inventions made in the field of Molecular Cytogenetics dated July 1, 1994.

10.5* Option Agreement between The Regents of The University of California and Imagenetics for Inventions
made in the field of Molecular Cytogenetics dated July 1, 1994.

10.6* Exclusive Option Agreement between Vysis and the University of California for the Glass Chromosome.

10.7* Exclusive License Agreement between the Regents of the University of California and Vysis, Inc. for
Molecular Cytogenetics Software dated June 1, 1995.

10.8* Exclusive License Agreement between the Regents of The University of California and ATC dated July 30,
1992, as amended, December 7, 1994.

10.9* License Agreement between The Trustees of Columbia University, The Salk Institute for Biological
Studies and Gene-Trak Systems dated October 7, 1988, as amended June 15, 1996.

10.10* Research and License Agreement between Gene-Trak Inc. and Public Health Research Institute dated July
14, 1994 and Letter re: Research and License Agreement dated July 18, 1994.

10.11* Exclusive Distributor Agreement between Vysis, Inc. and Fujisawa Pharmaceutical Co., Ltd. dated July
31, 1995.

+10.12* Sublicense Agreement between Ciba Corning Diagnostics Corp. and Vysis, Inc. dated May 24, 1996.

10.13* Software Development and Marketing Agreement between Digital Scientific Limited and Vysis, Inc. dated
January 1, 1996.

10.14* Form of Cooperation Agreement between the Company and Amoco Technology Company.

10.15* Form of Registration Rights Agreement between the Company and Amoco Technology Company.

10.16* Tax Allocation Agreement between the Company and Amoco Technology Company.

11.1 Statement Re Computation of Pro Forma Net Loss Per Share.

21.1* Subsidiaries of Vysis, Inc.

23.1 Consent of Price Waterhouse LLP

23.2* Consent of Mayer, Brown & Platt (appears in Exhibit 5.1).

23.3 Consent of McCutchen, Doyle, Brown & Enerson

24.1* Power of Attorney.

27.1* Financial Data Schedule.
</TABLE>

- ------------------------

* previously filed

** to be filed by amendment

+ confidential treatment requested

(b) Financial Statement Schedules

The following financial statement schedules of the Company are filed as part
of this Registration Statement and should be read in conjunction with the
Consolidated Financial Statements of the Company:

II-3
<PAGE>
SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS

Schedules other than those listed above have been omitted for the reason
that they are not required or are not applicable, or the required information is
shown in the financial statements or notes thereto.

ITEM 17. UNDERTAKINGS

Insofar as indemnification for liabilities arising under the Securities Act
of 1933, as amended, may be permitted to directors, officers and controlling
persons of the registrant pursuant to the foregoing provisions, or otherwise,
the registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
registrant of expenses incurred or paid by a director, officer or controlling
person of the registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the Act and will
be governed by the final adjudication of such issue.

The undersigned registrant hereby undertakes that:

(1) For purposes of determining any liability under the Securities Act of
1933, as amended, the information omitted from the form of prospectus
filed as part of this Registration Statement in reliance upon Rule 430A
and contained in a form of prospectus filed by the registrant pursuant to
Rule 424(b)(1) or (4) or 497(h) under the Securities Act of 1933, as
amended, shall be deemed to be part of this registration statement as of
the time it was declared effective.

(2) For purposes of determining any liability under the Securities Act of
1933, as amended, each post-effective amendment that contains a form of
prospectus shall be deemed to be a new registration statement relating to
the securities offered therein, and the offering of such securities at
that time shall be deemed to be the initial bona fide offering thereof.

The undersigned registrant hereby undertakes to provide to the Underwriters
at the closing specified in the underwriting agreement certificates in such
denominations and registered in such names as required by the Underwriters to
permit prompt delivery to each purchaser.

II-4
<PAGE>
SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant
certifies that it has duly caused this registration statement, or amendment
thereto, to be signed on its behalf by the undersigned, thereunto duly
authorized, in Downers Grove, Illinois on January 6, 1998.

<TABLE>
<S> <C> <C>
VYSIS, INC.

By: /s/ JOHN L. BISHOP
-----------------------------------------
Name: John L. Bishop
TITLE: PRESIDENT AND CHIEF EXECUTIVE
OFFICER
</TABLE>

PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, THIS
REGISTRATION STATEMENT HAS BEEN SIGNED BY THE FOLLOWING PERSONS IN THE
CAPACITIES AND ON THE DATE INDICATED.

<TABLE>
<CAPTION>
SIGNATURES TITLE (CAPACITY) DATE
- ------------------------------ -------------------------- -------------------

<C> <S> <C>
President, Chief Executive
/s/ JOHN L. BISHOP Officer and Director
- ------------------------------ (Principal Executive January 6, 1998
John L. Bishop Officer and Director)

Vice President of Finance
/s/ JAMES J. HABSCHMIDT and Chief Financial
- ------------------------------ Officer January 6, 1998
James J. Habschmidt (Principal Financial and
Accounting Officer)

*
- ------------------------------ Director January 6, 1998
William M. Bartlett

*
- ------------------------------ Director January 6, 1998
Robert C. Carr

- ------------------------------ Director January , 1998
Kenneth L. Melmon

*
- ------------------------------ Director January 6, 1998
Walter R. Quanstrom
</TABLE>

II-5
<PAGE>

<TABLE>
<CAPTION>
SIGNATURES TITLE (CAPACITY) DATE
- ------------------------------ -------------------------- -------------------

<C> <S> <C>
*
- ------------------------------ Director January 6, 1998
Frank J. Sroka

*
- ------------------------------ Director January 6, 1998
Richard C. Williams
</TABLE>

*By: /s/ JOHN L. BISHOP
-------------------------
John L. Bishop
ATTORNEY-IN-FACT

II-6
<PAGE>
VYSIS, INC.
SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS
FOR THE YEARS ENDED DECEMBER 31, 1994, 1995 AND 1996
AND THE NINE MONTHS ENDED SEPTEMBER 30, 1997
(In thousands)

<TABLE>
<CAPTION>
BALANCE AT BALANCE AT
DESCRIPTION OF BEGINNING END OF
ALLOWANCE AND RESERVES OF PERIOD ADDITIONS DEDUCTIONS PERIOD
- ------------------------------------------------------------------ ------------- ------------- ------------- -------------
<S> <C> <C> <C> <C>
1994
Allowance for doubtful accounts................................... $ 115 $ 50 $ 5 $ 160

1995
Allowance for doubtful accounts................................... $ 160 $ 60 $ -- $ 220

1996
Allowance for doubtful accounts................................... $ 220 $ -- $ 64 $ 156

Nine months ended September 30, 1997
Allowance for doubtful accounts................................... $ 156 $ 67 $ 41 $ 182
</TABLE>

II-7
<PAGE>
EXHIBIT INDEX

3.1.1* Certificate of Incorporation of Vysis, Inc. (formerly Framingham Development Company) filed April 18,
1991.

3.1.2* Certificate of Amendment of Certificate of Incorporation filed March 30, 1994.

3.1.3* Certificate of Merger filed February 1, 1996.

3.1.4* Certificate of Amendment of Certificate of Incorporation filed February 29, 1996.

3.1.5* Certificate of Correction of Certificate of Amendment filed July 22, 1996.

3.1.6* Certificate of Amendment of Certificate of Incorporation filed September 16, 1997.

3.1.7* Certificate of Designations of Series B Preferred Stock, filed September 17, 1997.

3.1.8* Certificate of Amendment of Certificate of Incorporation filed November 21, 1997.

3.2 Bylaws of Vysis, Inc.

4.1* Form of Common Stock Certificate.

5.1* Opinion of Mayer, Brown & Platt.

10.1* Vysis, Inc. 1996 Stock Incentive Plan.

10.2* Industrial Building Lease between American National Bank and Trust Company of Chicago and Vysis, Inc.
dated November 29, 1994.

10.3* License Agreement for Chromosome Analysis Technology with Chromosome-Specific Probes between ATC and
The Regents of The University of California dated August 15, 1989, as amended October 6, 1989; July
1, 1991; April 15, 1992; June 1, 1994; June 6, 1994; June 28, 1994; July 1, 1994; September 1, 1994.

10.4* Exclusive License Agreement between The Regents of The University of California and Imagenetics for
Inventions made in the field of Molecular Cytogenetics dated July 1, 1994.

10.5* Option Agreement between The Regents of The University of California and Imagenetics for Inventions
made in the field of Molecular Cytogenetics dated July 1, 1994.

10.6* Exclusive Option Agreement between Vysis and the University of California for the Glass Chromosome.

10.7* Exclusive License Agreement between the Regents of the University of California and Vysis, Inc. for
Molecular Cytogenetics Software dated June 1, 1995.

10.8* Exclusive License Agreement between the Regents of The University of California and ATC dated July
30, 1992, as amended, December 7, 1994.

10.9* License Agreement between The Trustees of Columbia University, The Salk Institute for Biological
Studies and Gene-Trak Systems dated October 7, 1988, as amended June 15, 1996.

10.10* Research and License Agreement between Gene-Trak Inc. and Public Health Research Institute dated July
14, 1994 and Letter re: Research and License Agreement July 18, 1994.

10.11* Exclusive Distributor Agreement between Vysis, Inc. and Fujisawa Pharmaceutical Co., Ltd. dated July
31, 1995.

+10.12* Sublicense Agreement between Ciba Corning Diagnostics Corp. and Vysis, Inc. dated May 24, 1996.

10.13* Software Development and Marketing Agreement between Digital Scientific Limited and Vysis, Inc. dated
January 1, 1996.

10.14* Form of Cooperation Agreement between the Company and Amoco Technology Company.
</TABLE>

<PAGE>

<TABLE>
<CAPTION>
EXHIBIT
NUMBER DESCRIPTION OF DOCUMENT
- ----------- -----------------------------------------------------------------------------------------------------
<S> <C>
10.15* Form of Registration Rights Agreement between the Company and Amoco Technology Company.

10.16* Tax Allocation Agreement between the Company and Amoco Technology Company.

11.1 Statement Re Computation of Per Share Net Loss.

21.1* Subsidiaries of Vysis, Inc.

23.1 Consent of Price Waterhouse LLP

23.2* Consent of Mayer, Brown & Platt (appears in Exhibit 5.1).

23.3 Consent of McCutchen, Doyle, Brown & Enerson

24.1* Power of Attorney.

27.1* Financial Data Schedule.
</TABLE>

- ------------------------

* previously filed

** to be filed by amendment

+ confidential treatment requested

<PAGE>

BYLAWS

VYSIS, INC.

ARTICLE I
OFFICES

Section 1. The registered office of the Corporation shall be in the City
of [Wilmington, County of New Castle,] State of Delaware. The Corporation may
also have offices at such other places both within and without the State of
Delaware as the Board of Directors may from time to time determine or the
business of the Corporation may require.

ARTICLE II
STOCKHOLDERS

Section 1. TIME AND PLACE OF MEETINGS. All meetings of the
stockholders for the election of directors or for any other purpose shall be
held at such time and place, within or without the State of Delaware, as shall
be designated by the Board of Directors. In the absence of a designation of a
place for any such meeting by the Board of Directors, each such meeting shall be
held at the principal office of the Corporation.

Section 2. ANNUAL MEETINGS. An annual meeting of stockholders shall be
held for the purpose of electing directors and transacting such other business
as may properly be brought before the meeting. The date of the annual meeting
shall be determined by the Board of Directors.

Section 3. SPECIAL MEETINGS. Special meetings of the stockholders, for
any purpose or purposes, unless otherwise prescribed by law or by the
Corporation's Certificate of Incorporation (as the same may be amended from time
to time, the "CERTIFICATE OF INCORPORATION"), may be called by the Chairman of
the Board, the President or by resolution of the Board of Directors, and shall
be called by the Chairman of the Board, the President or the Secretary at the
request in writing of a majority of the Board of Directors.

Section 4. NOTICE OF MEETINGS. Written notice of each meeting of the
stockholders stating the place, date and time of the meeting shall be given not
less than ten nor more than sixty days before the date of the meeting, to each
stockholder entitled to vote at such meeting. The notice of any special meeting
of stockholders shall state the purpose or purposes for which the meeting is
called. Business transacted at any special meeting of stockholders shall be
limited to the purposes stated in the notice. Neither the business to be
transacted at, nor the purpose of, an annual or special meeting of stockholders
need be specified in any written waiver of notice.

<PAGE>

Section 5. QUORUM; ADJOURNMENT. The holders of shares of capital stock
having a majority of the votes which could be cast by the holders of all shares
of capital stock of the Corporation, present in person or represented by proxy,
shall constitute a quorum at all meetings of the stockholders for the
transaction of business, except as otherwise required by these Bylaws, the
Certificate of Incorporation or the Delaware General Corporation Law as from
time to time in effect (the "DELAWARE LAW"). If a quorum is not represented,
the holders of the stock present in person or represented by proxy at the
meeting and entitled to vote thereat shall have power, by the affirmative vote
of the holders of a majority of such stock, to adjourn the meeting to another
time and/or place, without notice other than announcement at the meeting, except
as hereinafter provided, until a quorum shall be present or represented. At
such adjourned meeting, at which a quorum shall be present or represented, any
business may be transacted which might have been transacted at the original
meeting. If the adjournment is for more than thirty days, or if after the
adjournment a new record date is fixed for the adjourned meeting, a notice of
the adjourned meeting shall be given to each stockholder of record entitled to
vote at the meeting. Withdrawal of stockholders from any meeting shall not
cause the failure of a duly constituted quorum at such meeting.

Section 6. VOTING. At all meetings of the stockholders, each
stockholder shall be entitled to vote, in person, or by proxy appointed in an
instrument in writing subscribed by the stockholder or otherwise appointed in
accordance with Section 212 of the Delaware Law, each share of voting stock
owned by such stockholder of record on the record date for the meeting. Each
stockholder shall be entitled to one vote for each share of voting stock held by
such stockholder, unless otherwise provided in the Delaware Law or the
Certificate of Incorporation. When a quorum is present at any meeting, the
affirmative vote of the holders of a majority of the stock having voting power
present in person or represented by proxy shall decide any question brought
before such meeting, unless the question is one upon which, by express provision
of law or of the Certificate of Incorporation, a different vote is required, in
which case such express provision shall govern and control the decision of such
question. Any stockholder who is in attendance at a meeting of stockholders
either in person or by proxy, but who abstains from the vote on any matter,
shall not be deemed present or represented at such meeting for purposes of the
preceding sentence with respect to such vote, but shall be deemed present or
represented at such meeting for all other purposes. The Corporation shall, in
advance of any meeting of stockholders, appoint one or more inspectors to act at
the meeting and make a written report thereof, in accordance with the Delaware
Law.

Section 7. INFORMAL ACTION BY STOCKHOLDERS. Any action required to be
taken at a meeting of the stockholders, or any other action which may be taken
at a meeting of the stockholders, may be taken without a meeting, without prior
notice and without a vote, if a consent in writing, setting forth the action so
taken, shall be signed by the holders of outstanding stock having not less than
the minimum number of votes that would be necessary to authorize or take such
action at a meeting at which all shares entitled to vote thereon were present

-2-

<PAGE>

and voted. Prompt notice of the taking of the corporate action without a
meeting by less than unanimous written consent shall be given to those
stockholders who have not consented in writing.

ARTICLE III
DIRECTORS

Section 1. GENERAL POWERS. The business and affairs of the Corporation
shall be managed and controlled by or under the direction of its Board of
Directors, which may exercise all such powers of, and do all such acts and
things as may be done by, the Corporation and do all such lawful acts and things
as are not by law or by the Certificate of Incorporation or by these Bylaws
directed or required to be exercised or done by the stockholders.

Section 2. NUMBER, QUALIFICATION AND TENURE. The Board of Directors of
the Corporation shall consist of such number of directors as shall be determined
from time to time by resolution of the Board of Directors; PROVIDED, HOWEVER,
that such number shall not be less than three nor more than nine. The directors
shall be elected at the annual meeting of the stockholders and may be elected at
any special meeting of stockholders, except as otherwise provided herein, and
each director elected shall hold office until his or her successor is elected
and qualified or until his or her earlier death, termination, resignation or
removal from office. Directors need not be stockholders.

Section 3. VACANCIES AND NEWLY-CREATED DIRECTORSHIPS. Vacancies and
newly created directorships resulting from any increase in the number of
directors may be filled by a majority of the directors then in office, although
less than a quorum, or by a sole remaining director, and each director so chosen
shall hold office until his or her successor is elected and qualified or until
his or her earlier death, termination, resignation, retirement, disqualification
or removal from office. If there are no directors in office, then an election
of directors may be held in the manner provided by law.

Section 4. PLACE OF MEETINGS. The Board of Directors may hold
meetings, both regular and special, either within or without the State of
Delaware.

Section 5. MEETINGS. The Board of Directors shall hold a regular
meeting, to be known as the annual meeting, immediately following each annual
meeting of the stockholders. Other regular meetings of the Board of Directors
shall be held at such time and place as shall from time to time be determined by
the Board. No notice of regular meetings need be given, other than by
announcement at the immediately preceding regular meeting. Special meetings of
the Board may be called by the Chairman of the Board, or the President or by the
Secretary on the written request of a majority of the Board of Directors.
Notice of any special meeting of the Board shall be given at least twenty-four

-3-

<PAGE>

hours prior thereto, either in writing, or telephonically if confirmed promptly
in writing, to each director at the address shown for such director on the
records of the Corporation.

Section 6. WAIVER OF NOTICE; BUSINESS AND PURPOSE. Notice of any
meeting of the Board of Directors may be waived in writing signed by the person
or persons entitled to such notice either before or after the time of the
meeting. The attendance of a director at any meeting shall constitute a waiver
of notice of such meeting, except where a director attends a meeting for the
express purpose of objecting to the transaction of any business because the
meeting is not lawfully called or convened and at the beginning of the meeting
records such objection with the person acting as secretary of the meeting and
does not thereafter vote on any action taken at the meeting. Neither the
business to be transacted at, nor the purpose of, any regular or special meeting
of the Board need be specified in the notice or waiver of notice of such
meeting, unless specifically required by the Delaware Law.

Section 7. QUORUM AND MANNER OF ACTING. At all meetings of the Board
of Directors a majority of the total number of directors shall constitute a
quorum for the transaction of business. If a quorum shall not be present at any
meeting of the Board of Directors, the directors present thereat may adjourn the
meeting from time to time, without notice other than announcement at the
meeting, until a quorum shall be present. The act of a majority of the
directors present at any meeting at which there is a quorum shall be the act of
the Board of Directors, except as may be otherwise specifically provided by the
Delaware Law or by the Certificate of Incorporation. Withdrawal of directors
from any meeting shall not cause the failure of a duly constituted quorum at
such meeting. A director who is in attendance at a meeting of the Board of
Directors but who abstains from the vote on any matter shall not be deemed
present at such meeting for purposes of the preceding sentence with respect to
such vote, but shall be deemed present at such meeting for all other purposes.

Section 8. NOMINATION OF DIRECTORS AND PRESENTATION OF BUSINESS AT
STOCKHOLDER MEETINGS.

(a) Nominations of persons for election to the Board of Directors and
the proposal of business to be considered by the stockholders may be made
at an annual meeting of stockholders (i) pursuant to the Corporation's
notice of meeting, (ii) by or at the direction of the Board of Directors or
(iii) by any stockholder who was a stockholder of record at the time of the
giving of notice provided for in this Section 8, who is entitled to vote at
the meeting and who complied with the notice procedures set forth in this
Section 8.

(b) For nominations or other business to be properly brought before
an annual meeting by a stockholder pursuant to clause (iii) of paragraph
(a) of this Section 8, the stockholder must have given timely notice
thereof in writing to the Secretary of the Corporation. To be timely, a

-4-

<PAGE>

stockholder's notice shall be delivered to the Secretary at the principal
executive offices of the Corporation not less than 60 days nor more than 90
days prior to the first anniversary of the preceding year's annual meeting;
PROVIDED, HOWEVER, that in the event that the date of the annual meeting is
advanced by more than 30 days or delayed by more than 60 days from such
anniversary date, notice by the stockholder to be timely must be so
delivered not earlier than the 90th day prior to such annual meeting and
not later than the close of business or the later of (i) the 60th day prior
to such annual meeting or (ii) the 10th day following the day on which
public announcement of the date of such meeting is first made. Such
stockholder's notice shall set forth (i) as to each person whom the
stockholder proposes to nominate for election or reelection as a director
all information relating to such person that is required to be disclosed in
solicitations of proxies for election of directors, or is otherwise
required, in each case pursuant to Regulation 14A under the Securities
Exchange Act of 1934, as amended (the "EXCHANGE ACT") (including such
person's written consent to being named in the proxy statement as a
nominee and to serving as a director if elected); (ii) as to any other
business that the stockholder proposes to bring before the meeting, a brief
description of the business desired to be brought before the meeting, the
reasons for conducting such business at the meeting and any material
interest in such business of such stockholder and the beneficial owner, if
any, on whose behalf the proposal is made; (iii) as to the stockholder
giving the notice and the beneficial owner, if any, on whose behalf the
nomination or proposal is made (1) the name and address of such stockholder
as they appear on the Corporation's books, and of such beneficial owner and
(2) the class and number of shares of stock of the Corporation that are
owned beneficially and of record by such stockholder and such beneficial
owner. Notwithstanding anything in the second sentence of this paragraph
(b) to the contrary, in the event that the number of directors to be
elected to the Board of Directors is increased and there is no public
announcement naming all of the nominees for director or specifying the size
of the increased Board of Directors made by the Corporation at least 70
days prior to the first anniversary of the preceding year's annual meeting,
a stockholder's notice shall also be considered timely, but only with
respect to nominees for any new positions created by such increase, if it
shall be delivered to the Secretary at the principal executive offices of
the Corporation not later than the close of business on the 10th day
following the day on which the public announcement is first made by the
Corporation.

(c) Only such business shall be conducted at a special meeting of
stockholders as shall have been brought before the meeting pursuant to the
Corporation's notice of meeting. Nominations of persons for election to
the Board of Directors may be made at a special meeting of stockholders
with regard to which the Board of Directors has determined that directors
are to be elected (i) pursuant to the Corporation's notice of meeting, (ii)
by or at the direction of the Board of Directors or (ii) by any stockholder
who is a stockholder of record at the time of the giving of notice provided
for in this Section 8, who shall be entitled to vote for the election of
directors at the meeting and who complies with the notice procedures set
forth in this Section 8. In the event the Corporation calls a special

-5-

<PAGE>

meeting of stockholders for the purpose of electing one or more directors
to the Board of Directors, any such stockholder may nominate a person or
persons (as the case may be) for election to such position(s) as specified
in the Corporation's notice of meeting, if the stockholder's notice setting
forth the information and complying with the form described in paragraph
(b) of this Section 8 shall be delivered to the Secretary at the principal
executive offices of the Corporation not earlier than the 90th day prior to
such special meeting and not later than the close of business on the late
of (i) the 60th day prior to such special meeting or (ii) the 10th day
following the day on which public announcement is first made of the date of
the special meeting and of the nominees proposed by the Board of Directors
to be elected at such meeting.

(d) Only such persons who are nominated in accordance with the
procedures set forth in this Section 8 shall be eligible to serve as
directors and only such business shall be conducted at a meeting of
stockholders as shall have been brought before the meeting in accordance
with the procedures set forth in this Section 8. The Chairman of the
meeting of stockholders shall have the power and duty to determine whether
a nomination or any business proposed to be brought before the meeting was
made in accordance with the procedures set forth in this Section 8 and, if
any proposed nomination or business is not in compliance with this Section
8, to declare that such defective nominations or proposal shall be
disregarded.

(e) For purposes of this Section 8, "PUBLIC ANNOUNCEMENT" shall mean
disclosure in a press release reported by the Dow Jones News Service,
Associated Press or comparable national news service or in a document
publicly filed by the Corporation with the Securities and Exchange
Commission pursuant to Sections 13, 14 or 15(d) of the Exchange Act.

(f) Notwithstanding the foregoing provisions of this Section 8, (i)
if any class or series of stock has the right, voting separately by class
or series, to elect directors at an annual or special meeting of
stockholders, such directors shall be nominated and elected pursuant to the
terms of such class or series of stock; and (ii) a stockholder shall also
comply with all applicable requirements of the Exchange Act and the rules
and regulations thereunder with respect to the matters set forth in this
Section 8. Nothing in this Section 8 shall be deemed to affect any rights
of stockholders to request inclusion of proposals in the Corporation's
proxy statement pursuant to Rule 14a-8 under the Exchange Act.

Section 9. ORGANIZATION. The Chairman of the Board, if elected, shall
act as chairman at all meetings of the Board of Directors. If the Chairman of
the Board is not elected or, if elected, is not present, the President, or if
the President is not present, a director chosen by a majority of the directors
present, shall act as chairman at such meeting of the Board of Directors.

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<PAGE>

Section 10. COMMITTEES. The Board of Directors, by resolution adopted
by a majority of the whole Board of Directors, may designate one or more
committees, each such committee to consist of one or more directors. Except as
expressly limited by Delaware Law or the Certificate of Incorporation, any such
committee shall have and may exercise such powers as the Board of Directors may
determine and specify in the resolution designating such committee. The Board
of Directors, by resolution adopted by a majority of the whole Board of
Directors, also may designate one or more additional directors as alternate
members of any such committee to replace any absent or disqualified member at
any meeting of the committee, and at any time may change the membership of any
committee or amend or rescind the resolution designating the committee. In the
absence or disqualification of a member or alternate member of a committee, the
member or members thereof present at any meeting and not disqualified from
voting, whether or not such member or members constitute a quorum, may
unanimously appoint another director to act at the meeting in the place of any
such absent or disqualified member, provided that the director so appointed
meets any qualifications stated in the resolution designating the committee.
Each committee shall keep a record of proceedings and report the same to the
Board of Directors to such extent and in such form as the Board of Directors may
require. Unless otherwise provided in the resolution designating a committee, a
majority of all of the members of any such committee may select its Chairman,
fix its rules or procedure, fix the time and place of its meetings and specify
what notice of meetings, if any, shall be given.

Section 11. ACTION WITHOUT MEETING. Unless otherwise specifically
prohibited by the Certificate of Incorporation or these Bylaws, any action
required or permitted to be taken at any meeting of the Board of Directors or of
any committee thereof may be taken without a meeting, if all members of the
Board of Directors or such committee, as the case may be, execute a consent
thereto in writing setting forth the action so taken, and the writing or
writings are filed with the minutes of proceedings of the Board of Directors or
such committee.

Section 12. ATTENDANCE BY TELEPHONE. Members of the Board of Directors,
or any committee thereof, may participate in and act at any meeting of the Board
of Directors, or such committee, as the case may be, through the use of a
conference telephone or other communications equipment by means of which all
persons participating in the meeting can hear each other. Participation in such
meeting shall constitute attendance and presence in person at the meeting of the
person or persons so participating.

Section 13. COMPENSATION. By resolution of the Board of Directors,
irrespective of any personal interest of any of the members, the directors may
be paid their reasonable expenses, if any, of attendance at each meeting of the
Board of Directors and may be paid a fixed sum of attendance at meetings or a
stated salary as directors. These payments shall not preclude any director from
serving the Corporation in any other capacity and receiving compensation
therefor.

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<PAGE>

ARTICLE IV
OFFICERS

Section 1. ENUMERATION. The officers of the Corporation shall be
elected by the Board of Directors and shall include a President, one or more
Vice Presidents (the number and designation thereof to be determined by the
Board of Directors), a Secretary and a Treasurer. The Board of Directors may
also elect a Chairman of the Board, one or more Assistant Secretaries and
Assistant Treasurers and such other officers and agents as it may deem
appropriate. Any number of offices may be held by the same person.

Section 2. TERM OF OFFICE. The officers of the Corporation shall be
elected at the annual meeting of the Board of Directors and shall hold office
until their successors are elected and qualified, or until their earlier death,
termination, resignation or removal from office. Any officer or agent of the
Corporation may be removed at any time by the Board of Directors, with or
without cause. Any vacancy in any office because of death, resignation,
termination, removal, disqualification or otherwise, may be filled by the Board
of Directors for the unexpired portion of the term.

Section 3. CHAIRMAN OF THE BOARD. The Chairman of the Board, when and
if elected, shall preside at meetings of the Board of Directors and of
stockholders and shall have such other functions, authority and duties as may be
prescribed by the Board of Directors. The Chairman of the Board, if any, shall
be a member of the Board of Directors of the Corporation.

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<PAGE>

Section 4. PRESIDENT. The President shall be the chief executive
officer of the Corporation and, as such, shall have general supervision,
direction and control of the business and affairs of the Corporation, subject to
the control of the Board of Directors, shall have such other functions,
authority and duties as customarily appertain to the chief executive officer of
a business corporation and shall perform such duties and have such other powers
as may from time to time be prescribed by the Board of Directors.

Section 5. VICE PRESIDENTS. In the absence of the President or in the
event of the President's inability or refusal to act, the Vice President (or if
there be more than one, first, the Executive Vice Presidents, then the Senior
Vice Presidents, then the Vice Presidents, or in the absence of any designation,
then in the order of their most recent election) shall perform the duties of the
President and when so acting shall have all the powers of and be subject to all
the restrictions upon the President. A Vice President who is appointed as such
with respect to a particular area of responsibility or function of the
Corporation shall, subject to the authority of the Chairman and the President,
perform all duties and have all authority pertaining to the general and active
management of such area or function and shall see that all orders and
resolutions of the Board of Directors pertaining to such area or function are
carried into effect. The Vice Presidents shall perform such other duties and
have such other powers as the Board of Directors, the Chairman of the Board, or
the President may from time to time prescribe.

Section 6. SECRETARY. The Secretary shall: (a) keep a record of all
proceedings of the stockholders, the Board of Directors and any committees
thereof in one of more books provided for that purpose; (b) give, or cause to be
given, all notices that are required by law or these Bylaws to be given by the
Secretary; (c) be custodian of the corporate records and, if the Corporation has
a corporate seal, of the seal of the Corporation; (d) have authority to affix
the seal of the Corporation to all instruments the execution of which requires
such seal and to attest such affixing of the seal; (e) keep a register of the
post office address of each stockholder which shall be furnished to the
Secretary by such stockholder; (f) sign, with the Chairman or the President or
any Vice President, or any other officer thereunto authorized by the Board of
Directors, any certificates for shares of the Corporation, or any deeds,
mortgages, bonds, contracts or other instruments which the Board of Directors
has authorized to be executed by the signature of more than one officer; (g)
have general charge of the stock transfer books of the Corporation; (h) have
authority to certify as true and correct, copies of the Bylaws, or resolutions
of the stockholders, the Board of Directors and committees thereof, and of other
documents of the Corporation; and (i) in general, perform the duties incident to
the office of secretary and such other duties as from time to time may be
prescribed by the Board of Directors, the Chairman of the Board or the
President. The Board of Directors may give general authority to any other
officer to affix the seal of the Corporation and to attest such affixing of the
seal.

Section 7. ASSISTANT SECRETARY. The Assistant Secretary, or if there
shall be more than one, each Assistant Secretary in the absence of the Secretary
or in the event of the Secretary's inability or refusal to act, shall have the
authority to perform the duties of the Secretary, subject to such limitations

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<PAGE>

thereon as may be imposed by the Board of Directors, and such other duties as
may from time to time be prescribed by the Board of Directors, the Chairman of
the Board, the President or the Secretary.

Section 8. TREASURER. The Treasurer shall be the principal accounting
and financial officer of the Corporation. The Treasurer shall: (a) have charge
of and be responsible for the maintenance of adequate books of account for the
Corporation; (b) have charge and custody of all funds and securities of the
Corporation, and be responsible therefor and for the receipt and disbursement
thereof; and (c) perform the duties incident to the office of treasurer and such
other duties as may from time to time be prescribed by the Board of Directors,
the Chairman of the Board or the President. The Treasurer may sign with the
Chairman, the President or any Vice President, or any other officer thereunto
authorized by the Board of Directors, certificates for shares of the
Corporation. If required by the Board of Directors, the Treasurer shall give a
bond for the faithful discharge of his or her duties in such sum and with such
surety or sureties as the Board of Directors may determine.

Section 9. ASSISTANT TREASURER. The Assistant Treasurer, or if there
shall be more than one, each Assistant Treasurer, in the absence of the
Treasurer or in the event of the Treasurer's inability or refusal to act, shall
have the authority to perform the duties of the Treasurer, subject to such
limitations thereon as may be imposed by the Board of Directors, and such other
duties as may from time to time be prescribed by the Board of Directors, the
President or the Treasurer.

Section 10. GENERAL COUNSEL. The General Counsel shall be the chief
legal adviser of the Corporation as to all matters affecting the Corporation or
its business. In general, he shall perform all the duties incident to the
office of General Counsel and have such other duties as the Board of Directors,
the Chairman of the Board or the President may from time to time prescribe.

Section 11. OTHER OFFICERS AND AGENTS. Any officer or agent who is
elected or appointed from time to time by the Board of Directors and whose
duties are not specified in these Bylaws shall perform such duties and have such
powers as may from time to time be prescribed by the Board of Directors, the
Chairman of the Board or the President.

ARTICLE V
CERTIFICATES OF STOCK

Section 1. FORM. The shares of the Corporation shall be represented by
certificates; PROVIDED, HOWEVER, the Board of Directors may provide by
resolution or resolutions that some or all of any or all classes or series of
the Corporation's stock shall be uncertificated shares. Each certificate for
shares shall be consecutively numbered or otherwise identified. Certificates of
stock in the Corporation, shall be signed by or in the name of the Corporation
by the Chairman of the Board, the President or a Vice President and by the
Treasurer or an Assistant Treasurer or the Secretary or an Assistant Secretary

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<PAGE>

of the Corporation. Where a certificate is countersigned by a transfer agent,
other than the Corporation or an employee of the Corporation, or by a registrar,
the signatures of one or more officers of the Corporation may be facsimiles. In
case any officer, transfer agent or registrar who has signed or whose facsimile
signature has been placed upon a certificate shall have ceased to be such
officer, transfer agent or registrar before such certificate is issued, the
certificate may be issued by the Corporation with the same effect as if such
officer, transfer agent or registrar were such officer, transfer agent or
registrar at the date of its issue.

Section 2. TRANSFER. Upon surrender to the Corporation or the transfer
agent of the Corporation of a certificate for shares duly endorsed or
accompanied by proper evidence of succession, assignment or authority to
transfer, it shall be the duty of the Corporation, subject to any restriction
imposed by law or by contract, to issue a new certificate of stock or
uncertificated shares in place of any certificate therefor issued by the
Corporation to the person entitled thereto, cancel the old certificate and
record the transaction in its stock transfer books.

Section 3. REPLACEMENT. In case of the loss, destruction, mutilation
or theft of a certificate for any stock of the Corporation, a new certificate of
stock or uncertificated shares in place of any certificate theretofore issued by
the Corporation may be issued upon the surrender of the mutilated certificate
or, in the case of loss, destruction or theft of a certificate, upon
satisfactory proof of such loss, destruction or theft and upon such terms as the
Board of Directors may prescribe. The Board of Directors may in its discretion
require the owner of the lost, destroyed or stolen certificate, or his legal
representative, to give the Corporation a bond, in such sum and in such form and
with such surety or sureties as it may direct, to indemnify the Corporation
against any claim that may be made against it with respect to the certificate
alleged to have been lost, destroyed or stolen.

ARTICLE VI
INDEMNIFICATION OF DIRECTORS, OFFICERS, EMPLOYEES AND AGENTS

Section 1. THIRD PARTY ACTIONS. The Corporation shall indemnify any
person who was or is a party or is threatened to be made a party to any
threatened, pending, or completed action, suit or proceeding, whether civil,
criminal, administrative, or investigative, including all appeals (other than an
action, suit or proceeding by or in the right of the Corporation) by reason of
the fact that he is or was a director or officer, of the Corporation (and the
Corporation, in the discretion of the Board of Directors, may so indemnify a
person by reason of the fact that he is or was an employee or agent of the
Corporation or is or was serving at the request of the Corporation in any other
capacity for or on behalf of the Corporation), against expenses (including
attorneys' fees), judgments, decrees, fines, penalties, and amounts paid in
settlement actually and reasonably incurred by him in connection with such
action, suit or proceeding if he acted in good faith and in a manner which he
reasonably believed to be in or not opposed to the best interests of the
Corporation and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his conduct was unlawful; PROVIDED, HOWEVER, the

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Corporation shall be required to indemnify an officer or director in connection
with an action, suit or proceeding initiated by such person only if such action,
suit or proceeding was authorized by the Board of Directors. The termination of
any action, suit or proceeding by judgment, order, settlement, conviction, or
upon a plea of nolo contendere or its equivalent, shall not, of itself, create a
presumption that the person did not act in good faith or in a manner which he
reasonably believed to be in or not opposed to the best interests of the
Corporation and, with respect to any criminal action or proceeding, had
reasonable cause to believe that his conduct was unlawful.

Section 2. ACTIONS BY OR IN THE RIGHT OF THE CORPORATION. The
Corporation shall indemnify any person who was or is a party or is threatened to
be made a party to any threatened, pending, or completed action or suit,
including all appeals, by or in the right of the Corporation to procure a
judgment in its favor by reason of the fact that he is or was a director or
officer of the Corporation (and the Corporation, in the discretion of the Board
of Directors, may so indemnify a person by reason of the fact that he is or was
an employee or agent of the Corporation or is or was serving at the request of
the Corporation in any other capacity for or on behalf of the Corporation),
against expenses (including attorneys' fees) actually and reasonably incurred by
him in connection with the defense or settlement of such action or suit if he
acted in good faith and in a manner he reasonably believed to be in or not
opposed to the best interests of the Corporation, except that no indemnification
shall be made in respect of any claim, issue or matter as to which such person
shall have been finally adjudged to be liable for negligence or misconduct in
the performance of his duty to the Corporation unless and only to the extent
that the court in which such action or suit was brought, or any other court of
competent jurisdiction, shall determine upon application that, despite the
adjudication of liability but in view of all the circumstances of the case, such
person is fairly and reasonably entitled to indemnity for such expenses as such
court shall deem proper. Notwithstanding the foregoing, the Corporation shall
be required to indemnify an officer or director in connection with an action,
suit or proceeding initiated by such person only if such action, suit or
proceeding was authorized by the Board of Directors.

Section 3. INDEMNITY IF SUCCESSFUL. To the extent that a director,
officer, employee or agent of the Corporation has been successful on the merits
or otherwise in defense of any action, suit or proceeding referred to in Section
1 or 2 of this Article, or in defense of any claim, issue or matter therein, he
shall be indemnified against expenses (including attorneys' fees) actually and
reasonably incurred by him in connection therewith.

Section 4. STANDARD OF CONDUCT. Except in a situation governed by
Section 3 of this Article, any indemnification under Section 1 or 2 of this
Article (unless ordered by a court) shall be made by the Corporation only as
authorized in the specific case upon a determination that indemnification of the
director, officer, employee or agent is proper in the circumstances because he
has met the applicable standard of conduct set forth in Section 1 or 2, as
applicable, of this Article. Such determination shall be made (i) by a majority
vote of directors acting at a meeting at which a quorum consisting of directors
who were not parties to such action, suit or proceeding is present, or (ii) if

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such a quorum is not obtainable, or even if obtainable, a quorum of
disinterested directors so directs, by independent legal counsel in a written
opinion, or (iii) by the stockholders. The determination required by clauses
(i) and (ii) of this Section 4 may in either event be made by written consent of
the majority required by each clause.

Section 5. EXPENSES. Expenses (including attorneys' fees) of each
officer and director hereunder indemnified actually and reasonably incurred in
defending any civil, criminal, administrative or investigative action, suit or
proceeding or threat thereof shall be paid by the Corporation in advance of the
final disposition of such action, suit or proceeding upon receipt of an
undertaking by or on behalf of such person to repay such amount if it shall
ultimately be determined that he is not entitled to be indemnified by the
Corporation as authorized in this Article. Such expenses (including attorneys'
fees) incurred by employees and agents may be so paid upon the receipt of the
aforesaid undertaking and such terms and conditions, if any, as the Board of
Directors deems appropriate.

Section 6. NONEXCLUSIVITY. The indemnification and advancement of
expenses provided by, or granted pursuant to, other Sections of this Article
shall not be deemed exclusive of any other rights to which those seeking
indemnification or advancement of expenses may now or hereafter be entitled
under any law, bylaw, agreement, vote of stockholders or disinterested directors
or otherwise, both as to action in his official capacity and as to action in
another capacity while holding such office.

Section 7. INSURANCE. The Corporation may purchase and maintain
insurance on behalf of any person who is or was a director, officer, employee or
agent of the Corporation, or is or was serving at the request of the Corporation
as a director, officer, employee or agent of another Corporation, partnership,
joint venture, trust or other enterprise against any liability asserted against
him and incurred by him in any such capacity, or arising out of his status as
such, whether or not the Corporation would have the power to indemnify him
against such liability under the provisions of the Delaware Law.

Section 8. DEFINITIONS. For purposes of this Article, references to
"the Corporation" shall include, in addition to the resulting corporation, any
constituent corporation (including any constituent of a constituent) absorbed in
a consolidation or merger which, if its separate existence had continued, would
have had the power and authority to indemnify any or all of its directors,
officers, employees and agents, so that any person who was a director, officer,
employee or agent of such constituent corporation, or was serving at the request
of such constituent corporation in any other capacity, shall stand in the same
position under the provisions of this Article with respect to the resulting or
surviving corporation as such person would have had with respect to such
constituent corporation if its separate existence had continued as such
corporation was constituted immediately prior to such merger.

For purposes of this Article, references to "other capacities" shall
include serving as a trustee or agent for any employee benefit plan; references
to "fines" shall include any excise taxes assessed on a person with respect to

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<PAGE>

an employee benefit plan; and references to "serving at the request of the
Corporation" shall include any service as a director, officer, employee or agent
of the Corporation which imposes duties on, or involves services by such
director, officer, employee, or agent with respect to an employee benefit plan,
its participants, or beneficiaries. A person who acted in good faith and in a
manner he or she reasonably believed to be in the best interests of the
participants and beneficiaries of an employee benefit plan shall be deemed to
have acted in a manner "not opposed to the best interests of the Corporation" as
referred to in this Article.

Section 9. SEVERABILITY. If any provision hereof is invalid or
unenforceable in any jurisdiction, the other provisions hereof shall remain in
full force and effect in such jurisdiction, and the remaining provisions hereof
shall be liberally construed to effectuate the provisions hereof, and the
invalidity of any provision hereof in any jurisdiction shall not affect the
validity or enforceability of such provision in any other jurisdiction.

Section 10. AMENDMENT. The right to indemnification conferred by this
Article shall be deemed to be a contract between the Corporation and each person
referred to herein until amended or repealed, but no amendment to or repeal of
these provisions shall apply to or have any effect on the right to
indemnification of any person with respect to any liability or alleged liability
of such person for or with respect to any act or omission of such person
occurring prior to such amendment or repeal.

ARTICLE VII
GENERAL PROVISIONS

Section 1. FISCAL YEAR. The fiscal year of the Corporation shall end
on December 31 of each year unless otherwise fixed from time to time by
resolution of the Board of Directors.

Section 2. CORPORATION SEAL. The corporate seal of the Corporation
shall be inscribed with the name of the Corporation and the words "Corporate
Seal" and "Delaware". The seal may be used by causing it or a facsimile thereof
to be impressed or affixed or in any other manner reproduced.

Section 3. NOTICES AND MAILING. Except as otherwise provided by
Delaware Law, the Certificate of Incorporation or these Bylaws, all notices
required to be given by any provision of these Bylaws shall be deemed to have
been given (i) when received, if given in person, (ii) on the date of
acknowledgment of receipt, if sent by telex, facsimile or other wire
transmission, (iii) one day after delivery, properly addressed, to a reputable
courier for same day or overnight delivery, or (iv) three days after being
deposited, properly addressed, in the U.S. mail, certified or registered mail,
postage prepaid.

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Section 4. WAIVER OF NOTICE. Whenever any notice is required to be
given under the Delaware Law or the provisions of the Certificate of
Incorporation or these Bylaws, a waiver thereof in writing, signed by the person
or persons entitled to said notice, whether before or after the time stated
therein, shall be deemed equivalent to notice.

Section 5. INTERPRETATION. In these Bylaws, unless a clear contrary
intention appears, the singular number includes the plural number and VICE
VERSA, and reference to either gender includes the other gender.

ARTICLE VIII
AMENDMENTS

These Bylaws may be altered, amended or repealed or new Bylaws may be
adopted by the Board of Directors. The fact that the power to amend, alter,
repeal or adopt the Bylaws has been conferred upon the Board of Directors shall
not divest the stockholders of the same powers.

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EXHIBIT 11.1

VYSIS, INC.
STATEMENT RE COMPUTATION OF PRO FORMA NET LOSS PER SHARE
(IN THOUSANDS, EXCEPT NET LOSS PER SHARE)

<TABLE>
<CAPTION>
PRO FORMA FOR THE NINE
-------------------------------------
FOR THE YEAR MONTHS ENDED SEPTEMBER SUPPLEMENTAL
ENDED 30, ------------------
DECEMBER 31, ----------------------- FOR THE NINE
1996 1997 MONTHS ENDED
------------ ---------- SEPTEMBER 30, 1997
1996 ------------------
----------- (UNAUDITED)
(UNAUDITED)
<S> <C> <C> <C> <C>
Net loss per statement of operations.................. $ (18,181) $ (13,788) $ (11,462) $ (11,095)

Weighted average common shares outstanding:
Shares attributable to common stock outstanding..... 1,058 1,058 1,058 1,058
Shares attributable to common stock equivalents..... 4,929 4,929 4,929 4,929
Shares attributable to options pursuant to SEC Staff
Accounting Bulletin No. 83........................ 120 120 120 120
Shares to be issued in proposed offering............ -- -- -- 583
------------ ----------- ---------- --------
Total............................................... 6,107 6,107 6,107 6,690
------------ ----------- ---------- --------
------------ ----------- ---------- --------

Pro forma net loss per share.......................... $ (2.98) $ (2.26) $ (1.88)
------------ ----------- ----------
------------ ----------- ----------
Supplemental pro forma net loss per share............. $ (1.66)
--------
--------
</TABLE>

<PAGE>
EXHIBIT 23.1

CONSENT OF INDEPENDENT ACCOUNTANTS

We hereby consent to the use in the Prospectus constituting part of this
Registration Statement on Form S-1 of our report dated November 21, 1997,
relating to the consolidated financial statements of Vysis, Inc., which appears
in such Prospectus. We also consent to the application of such report to the
Financial Statement Schedule for the three years ended December 31, 1996 and the
nine months ended September 30, 1997 listed under Item 16(b) of this
Registration Statement when such schedule is read in conjunction with the
consolidated financial statements referred to in our report. The audits referred
to in such report also include this schedule. We also consent to the references
to us under the headings "Experts" and "Selected Financial Information" in such
Prospectus. However, it should be noted that Price Waterhouse LLP has not
prepared or certified such "Selected Financial Information."

PRICE WATERHOUSE LLP

Chicago, Illinois

January 6, 1998

<PAGE>
EXHIBIT 23.3

CONSENT OF EXPERTS

We consent to the reference to our firm under the caption, "Experts", with
respect to the sections entitled "Risk Factors--Uncertain Ability to Practice
Technology"; "Business--Ability to Practice Technology"; "Business--Litigation";
and "Business--Patents and Proprietary Technology" in the Registration Statement
on Form S-1 of Vysis, Inc. proposed to be filed on or about January 6, 1998.

<TABLE>
<S> <C> <C>
McCutchen, Doyle, Brown & Enersen, L.L.P.

By: /s/ WILLIAM E. THOMSON, JR.
--------------------------------------
William E. Thomson, Jr.
</TABLE>

Los Angeles, California
January 6, 1998