IMATRON INC
S-3, 1996-09-06
ELECTROMEDICAL & ELECTROTHERAPEUTIC APPARATUS
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As filed with the Securities and Exchange Commission on September 6, 1996
                                            --Registration No. __________

================================================================================

                                    FORM S-3

                       SECURITIES AND EXCHANGE COMMISSION

             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                                  IMATRON INC.
                 (Exact name of issuer specified in its charter)

             New Jersey                              94-2880078
      (State of incorporation)          (I.R.S. Employer Identification No.)

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

                           389 Oyster Point Boulevard
                      South San Francisco, California 94080
                                 (415) 583-9964
               (Address, including zip code and telephone number,
       including area code, of registrant's principal executive offices)

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

                                 S. Lewis Meyer
                      President and Chief Executive Officer
                                  Imatron Inc.
                           389 Oyster Point Boulevard
                      South San Francisco, California 94080
                                 (415) 583-9964
            (Name, address including zip code, and telephone number,
                   including area code, of agent for service)

                                   Copies to:

                              Roger S. Mertz, Esq.
                                Severson & Werson
                       One Embarcadero Center, 25th Floor
                         San Francisco, California 94111

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

Approximate  date of  commencement  of proposed  sale to the public:  As soon as
practicable after this Registration Statement becomes effective.


<PAGE>

If the only securities  being registered on this Form are being offered pursuant
to dividend or interest reinvestment plans, please check the following box: ( )

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, other than securities offered only in connection with dividend or interest
reinvestment plans, please check the following box: ( X )

                         CALCULATION OF REGISTRATION FEE
================================================================================

Title of Each                       Proposed       Proposed
Class of                            Maximum        Maximum
Securities to      Amount to        Offering       Aggregate        Amount of
Be                 Be               Price Per      Offering         Registration
Registered         Registered       Share          Price            Fee         
- -------------      ----------       ---------      ---------        ------------
Common Stock       3,810,155        $6.00(1)       $22,860,930(1)      $7,883
                   Shares
================================================================================

(1)  Estimated  pursuant to Rule 457(c) solely for purposes of  determining  the
     registration  fee, based on the average of the high and low sales prices on
     September 4, 1996, as reported on the NASDAQ National Market System.


The Registrant hereby amends this Registration Statement on such date or date(s)
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  Commission  acting  pursuant to said Section 8(a)
may determine.


                                       ii
<PAGE>

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.


                 SUBJECT TO COMPLETION, DATED September 6, 1996

                                   PROSPECTUS

                                3,810,155 Shares

                                  IMATRON INC.

                            Common Stock No Par Value

         This Prospectus relates to the sale of up to 3,810,155 shares of Common
Stock,  no par value,  of Imatron Inc. (the  "Company") by  shareholders  of the
Company (the  "Selling  Shareholders").  A total of 69,542  shares are currently
issued and outstanding (the "Outstanding Shares"); a total of 540,613 shares are
issuable  upon the  exercise  of  outstanding  warrants  (the  "Warrants")  (the
"Warrant  Shares");  and a total  of  3,200,000  shares  are  issuable  upon the
exercise of  outstanding  Common Stock exchange  rights (the "Exchange  Rights")
(the "Exchange Rights Shares"). All of the Outstanding Shares, the Warrants, and
the  Exchange  Rights  were  previously  issued by the  Company  to the  Selling
Shareholders  in private  transactions.  The  Outstanding  Shares,  the  Warrant
Shares,  and the Exchange  Rights  Shares are  collectively  referred to in this
Prospectus as the "Shares." The Selling  Shareholders  intend to sell the Shares
from  time  to time  in  open  market  and/or  private  sales,  or by any  other
appropriate method.

         The Company will receive  proceeds upon the exercise of the Warrants by
the Selling Shareholders, but will not receive any of the proceeds from the sale
of the Shares.  The Company has agreed to bear all of the expenses in connection
with the registration (but not the sale) of the Shares.

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

                 THESE SECURITIES INVOLVE A HIGH DEGREE OF RISK.
                               SEE "RISK FACTORS."

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

          THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE
            SECURITIES AND EXCHANGE COMMISSION NOR HAS THE COMMISSION
          PASSED UPON THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY
              REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

                The Date of this Prospectus is September 6, 1996


                                       1
<PAGE>



                                TABLE OF CONTENTS


AVAILABLE INFORMATION.......................................................  3

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE.............................  3

THE COMPANY.................................................................  4

RISK FACTORS................................................................  5

USE OF PROCEEDS............................................................. 11

OFFERING PRICE.............................................................. 11

SELLING SHAREHOLDERS.........................................................12

PLAN OF DISTRIBUTION........................................................ 15

EXPERTS..................................................................... 15

LEGAL OPINION............................................................... 15


                                       2

<PAGE>

                             AVAILABLE INFORMATION

         Imatron  Inc.   ("Imatron"   or  the   "Company")  is  subject  to  the
informational  requirements  of the  Securities  and  Exchange  Act of 1934,  as
amended (the "Exchange Act"), and, in accordance therewith, files reports, proxy
statements and other  information  with the  Securities and Exchange  Commission
(the "Commission").  Such reports,  proxy statements and other information filed
by the Company with the Commission can be inspected and copied at Room 1024, 450
Fifth Street, N.W.,  Washington,  D.C. 20549, and at the Regional Offices of the
Commission at Room 1204,  Everett McKinley Dirksen Building,  219 South Dearborn
Street, Chicago,  Illinois 60604; and Room 1102, 26 Federal Plaza, New York, New
York 10007.  Copies of such material can be obtained  from the Public  Reference
Section of the Commission, at 450 Fifth Street, N.W., Washington, D.C. 20549, at
prescribed rates.  Shares of the Company's Common Stock are traded on the NASDAQ
National  Market  System under the symbol  "IMAT."  Information  concerning  the
Company may also be obtained by contacting NASDAQ/NMS.

                INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

         The Company's  Annual  Report on Form 10-K for the year ended  December
31, 1995,  filed March 29, 1996 (File No.  0-12405) and all amendments  thereto;
the Company's  definitive  Proxy  Statement  filed pursuant to Section 14 of the
Exchange Act in connection with the Annual Meeting of shareholders  held on June
28, 1996, filed April 29, 1996; the Company's Report on Form 10-Q for the period
ended June 30, 1996,  filed August 14, 1996;  the Form 10-Q for the period ended
March 31, 1996,  filed on May 15, 1996;  and the  description  of the  Company's
Common Stock contained in a registration statement filed under the Exchange Act,
including  any  amendment  or report  filed for the  purpose  of  updating  such
description,  are hereby  incorporated  by reference into this  Prospectus.  All
documents  filed by the Company with the Commission  pursuant to Sections 13(a),
13(c),  14 or 15(d) of the  Exchange Act after the date of this  Prospectus  and
prior to the  termination  of the offering of Common Stock shall be deemed to be
incorporated  by reference into this Prospectus and to be a part hereof from the
date of filing of such documents, except the Board Compensation Committee Report
on  Executive  Compensation  and the  Performance  Graph  included  in the Proxy
Statement  pursuant  to Item 402(k) and (l) of  Regulation  S-K.  Any  statement
contained in a document  incorporated by reference  herein shall be deemed to be
modified or  superseded  for  purposes of this  Prospectus  to the extent that a
statement  contained  herein or in any other  subsequently  filed document which
also  is or is  deemed  to be  incorporated  by  reference  herein  modifies  or
supersedes such statement.  Any statement so modified or superseded shall not be
deemed,  except as so  modified  or  superseded,  to  constitute  a part of this
Prospectus.  The Company will provide  without charge to each person,  including
any beneficial owner, to whom this Prospectus is delivered, upon written or oral
request of such person,  a copy of any and all of the information  that has been
incorporated  by  reference  in  this  Registration  Statement  filed  with  the
Commission  under the Exchange  Act with respect to the Common Stock  offered by
the Prospectus,  other than certain  exhibits to such  documents.  Such requests
should be directed to the Chief  Financial  Officer,  Imatron  Inc.,  389 Oyster
Point Boulevard,  South San Francisco,  California 94080, telephone number (415)
583-9964.


                                       3
<PAGE>

                                   THE COMPANY

         Imatron  is a  technology-based  company  principally  engaged  in  the
business of designing,  manufacturing, and marketing a high performance computed
tomography  (CT)  scanner  that uses a scanning  electron  beam.  CT refers to a
diagnostic  imaging device in which  cross-sectional  (tomographic)  images of a
patient's  anatomy are acquired from  multiple  intensity  readings  taken as an
x-ray source rotates around the patient. Ultrafast CT technology is more than 20
times faster than conventional  computed  tomography,  enabling users to perform
certain tests involving  organs in motion (e.g. the heart) that no other medical
imaging equipment is able to perform.

         For over a decade,  the  scanner  has been used in large and  mid-sized
hospitals and free standing imaging clinics.  The Company also provides service,
parts,  and maintenance to hospitals and clinics that operate its scanners.  The
technological  advantage provided by high-speed  tomography now provides Imatron
the opportunity to develop a new and additional  market,  by performing  simple,
low cost,  non-invasive  screening to detect the earliest signs of heart disease
by means of the  Coronary  Artery Scan  ("CAS").  This vast new market  involves
activity in both diagnostic services and equipment manufacturing.

         The Company is also  engaged in the related  businesses  of  performing
research and development for itself and others in the field of CT devices and of
licensing its patents and know-how in the field of imaging sciences.

         Imatron was incorporated in New Jersey in February, 1983. Its executive
offices  are  located  at 389  Oyster  Point  Boulevard,  South  San  Francisco,
California 94080, and its telephone number is (415) 583-9964.

         In 1993, Imatron organized  HeartScan  Imaging,  Inc. as a wholly-owned
subsidiary  to develop and operate a network of  company-owned  coronary  artery
disease  risk  assessment  centers  in  cooperation  and  conjunction  with  the
established medical (primarily  cardiology)  community in specific  metropolitan
areas. In that same year, HeartScan opened a test facility adjacent to Imatron's
headquarters.  In July,  1995, it opened its first coronary  artery disease risk
assessment center in Seattle, Washington. In January, 1996, it opened its second
facility in Houston, Texas. It opened similar facilities in Washington, D.C. and
Pittsburgh,  Pennsylvania,  in May, 1996.  HeartScan's  centers  deliver the CAS
diagnostic  test  together  with other risk factor tests in a manner  consistent
with established channels of patient referral,  as well as with the new channels
of  patient  referral  being  created  by health  care  reform and the growth of
managed-care systems.

         A  significant  component of  HeartScan's  approach is to offer the CAS
procedure and a full battery of coronary artery disease risk assessment  testing
to consumers without necessarily  requiring a physician's  referral, an approach
designed to result in more rapid  acceptance of the test and a shorter return on
the  investment  cycle.  This is  achieved  by means of two broad  and  mutually
supportive  approaches - increasing  the number of coronary  artery disease risk
assessment  centers in operation,  which in turn,  both directly and indirectly,
increases  the  demand  for  Imatron's   C-150/Evolution  scanner  currently  in
distribution.  HeartScan management believes that the market for coronary artery
disease risk assessment centers is very large and that HeartScan's comprehensive
heart disease screening approach is both revolutionary and highly effective.

                                       4

<PAGE>

         HeartScan  Imaging,  Inc. was incorporated in Delaware in April,  1993.
Its executive offices are currently co-located with those of Imatron Inc. at 389
Oyster Point Boulevard, South San Francisco, California 94080, and its telephone
number is (415) 583-9964.


                                  RISK FACTORS

         The securities offered hereby are speculative and involve a high degree
of risk.  Prospective  investors  may  lose  all or a part of their  investment.
Consequently,  the  following  factors,  in  addition  to the other  information
contained in this Prospectus,  should be considered  carefully in evaluating the
Company and its business before purchasing the securities offered hereby:

         Short Operating History. Imatron was incorporated in February, 1983 and
in April, 1983 became the successor to Imatron Associates, a limited partnership
established in February,  1981. Imatron operated as a development-stage  company
until the fourth  quarter of 1984, at which time it recognized  its initial sale
of an ULTRAFAST CT7 scanner. Imatron incurred losses each quarter from inception
in February,  1981 through December 31, 1990. Its first recorded profitable year
was the year ended  December 31, 1991 during which a $4,000,000  payment for the
licensing  of  technology  to Siemens  Corporation  was  received.  The  Company
incurred net losses of $2,871,000 and $6,523,000 in the years ended December 31,
1993 and 1992,  respectively.  1994 was the Company's  first year of profit from
operations. In 1995, the Company incurred a net loss of $2,449,000.  Through the
first six months of 1996 the Company recorded a net loss of $5,023,000. There is
no assurance that Imatron can return to profitable  operations in the future. In
the past, Imatron has funded its losses primarily through the sale of securities
in three  public  offerings  and a number of  private  placements,  through  the
exercise of options and  warrants,  through the 1991 license for medical uses of
its electron-beam technology to Siemens Corporation, and through revolving lines
of credit. In 1995, the Company raised $9,882,000 (net of offering costs) in two
offerings of Common Stock to certain institutional investors.  Through the first
six months of 1996, the Company raised  $14,570,000  (net of offering  costs) in
one  public  offering  and a  number  of  private  placements  to  institutional
investors.  In  addition,  during the third  quarter of 1996 the Company  gained
$1,757,000 from the sale of its interest in InVision Technologies, Inc., a joint
venture it helped  establish in 1990. The Company has an accumulated  deficit of
$62,580,000.

         Management   believes  that  cash,  cash   equivalents  and  short-term
investments  existing  at  December  31, 1995 and the  estimated  proceeds  from
ongoing  sales of products  and  services in 1996 will  provide the Company with
sufficient  cash for  operating  activities  and  capital  requirements  through
December 31, 1996.

         Need for Additional Financing.  To satisfy the Company's future capital
and  operating  requirements,  profitable  operations  or  additional  public or
private  financing  will be required.  If future public or private  financing is
required by the Company,  holders of the  Company's  securities  may  experience
dilution. If such financing cannot be obtained,  the Company may seek to sell or
license additional portions of its technology,  to sell some or all of its other
assets or to merge with another company. In addition,  HSI will need substantial
additional  financing  to fund  its plan to own and  operate  CAS  clinics.  The
Company and HSI completed an offering of HSI 

                                       5

<PAGE>

Series A Preferred  Stock to certain  institutional  investors in June 1996. The
offering  raised a total of  $14,866,000  (net of offering  costs).  Imatron has
contributed  the net proceeds  from the offering to HSI. In the event HSI cannot
raise necessary  additional  financing in the future it will have to curtail its
expansion activities.

         Material  Dependence Upon Key Personnel.  The Company has been and will
continue  to be  materially  dependent  upon  the  technical  expertise  of  its
engineering  management  personnel.  The loss of a  significant  number  of such
personnel would have a materially adverse effect upon the Company's business and
future prospects. The Company does not maintain key-man life insurance.

         High Cost of Scanner. The distributor list price of Imatron's ULTRAFAST
CT  scanner  is  significantly  higher  than  that  of  commercially   available
conventional  CT  scanners  and  higher  than  the  price  of  "top-of-the-line"
scanners.  Such pricing may limit the market for  Imatron's  product.  Potential
customers'  budgetary   limitations,   including  those  imposed  by  government
regulation,  may often  compel  the  purchase  of lower  cost,  conventional  CT
scanners.

         Limited  Clinical  Demonstration  of Certain  Advantages  of  Company's
Scanner.  The  Company's  scanners have been used in a clinical  environment  on
humans since April,  1983.  Clinical use of the C-100 XL scanner  model began in
February  1989 and  twenty-seven  C-150  scanners are  currently  installed in a
clinical  setting.  The Company believes that market acceptance of the ULTRAFAST
CT  scanner   continues  to  depend  in  substantial   part  upon  the  clinical
demonstration  of  certain  asserted  technological  advantages  and  diagnostic
capabilities.  There is no assurance  that these  advantages  will result in the
development  of a  significant  market for the  ULTRAFAST CT that will allow the
Company to operate profitably.

         Product  Liability  Risks.  As a  manufacturer  and marketer of medical
diagnostic  equipment,  the Company is subject to  potential  product  liability
claims.  For example,  the  exposure of normal human tissue to x-rays,  which is
inherent  in the use of CT  scanners  for  diagnostic  imaging,  may  result  in
potential  injury to  patients,  thereby  subjecting  the  Company  to  possible
liability  claims.  The Company  presently  maintains primary and excess product
liability  insurance with  aggregate  limits of $5,000,000  per  occurrence.  No
assurance can be given that the Company's product liability  insurance  coverage
will  continue  to be  available  or, if  available,  that it can be obtained in
sufficient amounts or at reasonable cost or that it will prove sufficient to pay
any claims that may arise.

         Reliance On Patents And Proprietary Technology.  Imatron relies heavily
on proprietary technology which it attempts to protect through patents and trade
secrets.

         In February  1981,  the Company was granted the  exclusive use for five
years and  non-exclusive  use  thereafter  of  certain  technology  and a patent
pending owned by the University of California  (UC) under the terms of a license
agreement  between  UC  and  Emersub,  a  wholly-owned  subsidiary  of a  former
principal shareholder of the Company, and a sublicense agreement between Emersub
and Imatron Associates (the predecessor to the Company),  respectively.  In June
1986, the license and sublicense agreements were amended to extend the Company's
exclusive use of the technology  through the remaining 9-year life of the patent
in exchange for modified  minimum  annual royalty  payments.  Under the terms of
Emersub's  license with UC,  Emersub was  obligated  to make certain  additional
payments in connection with the license. In 

                                       6

<PAGE>

October 1990,  pursuant to subsequent  amendments of the license and  sublicense
agreements,  the  Company  issued an  aggregate  of  132,813  shares of Series A
Preferred  Stock to UC and  Emersub  in  satisfaction  of this  obligation.  The
University of California  converted  their 125,000 Series A Preferred Stock into
625,000  common stock  shares in 1993.  Emersub  converted  their 7,813 Series A
Preferred Stock into 39,065 common stock shares in September 1995.

         In addition, the sublicense agreement, as amended, requires the Company
to pay annual  royalties  to Emersub  equal to 2.125% of net sales of certain of
the Company's  products.  The Company's  Chairman of the Board,  Dr.  Douglas P.
Boyd, receives 6% of all of the royalties paid by Emersub to UC. Loss by Imatron
of its rights under the patent as a result of termination of its sublicense from
Emersub,  or the underlying  license,  could have a material adverse effect upon
Imatron's  business and future  prospects.  There are no present  disputes  with
either UC or Emersub.

         Development of portions of the technology  covered by the UC patent and
sublicensed  to Imatron has been funded in  substantial  part  through  research
financing made available to UC by the National Institutes of Health. As a result
of such  financing,  it is possible that the U. S. Government may assert certain
claims in such UC patents,  including  the right to a  royalty-free  license for
governmental use.

         In addition,  Imatron holds  twenty-seven U.S. Patents of its own (each
with a  remaining  life in excess of 3 years) and has filed  three  U.S.  patent
applications  covering  various  integral  components of the scanner  including,
among others,  its electron  beam assembly and its x-ray  detector and has filed
applications  corresponding  to several of these  patents  and  applications  in
various European Patent Convention countries,  Canada and Japan. There can be no
assurance that any such  applications will result in the issuance of a patent to
the Company.  Imatron's patents and patent  applications have not been tested in
litigation and no assurance can be given that patent  protection  will be upheld
or will be as extensive as claimed. Furthermore, no assurance can be given as to
the Company's ability to finance  litigation  against parties which may infringe
upon  such  patents  or  parties  which  may claim  that the  Company's  scanner
infringes upon their patents.  However,  the agreement signed by the Company and
Siemens Corporation in March 1991 allows Siemens Corporation to enter litigation
in favor of Imatron.

         On March 31,  1995,  the Company and  Siemens  Corporation  ("Siemens")
entered into an agreement (the "Memorandum of  Understanding")  relating in part
to certain of the  Company's  patents.  Pursuant to the  agreement,  the Company
transferred  to  Siemens  five  patents,  two of  which  cover  features  of the
Company's C-150 scanner, in consideration of the cancellation by Siemens of a $4
million term loan to the Company.  As part of the agreement  Siemens  granted to
the Company a non-exclusive, irrevocable, perpetual license to the five patents.
The license is subject to a royalty of $20,000 for each new C-150 unit  produced
by the Company beginning with the twenty-first C-150 unit produced in any year.

         Siemens has recently asserted a claim against the Company regarding the
lapse of certain foreign registrations of one of the patents assigned to Siemens
by the  Company in  connection  with the March 31,  1995  agreement  between the
companies. The technology involved in the patent is not used presently in any of
the Company's products. The Company believes that it can provide a new patent to
Siemens to replace the lapsed  patent.  While the resolution of the claim is not
expected to have a material effect on the Company's  financial position it could
however,  

                                       7

<PAGE>

have a material  effect on the  results of  operations  of a  particular  future
period if resolved unfavorably.

         In the  event  some or all of the  Company's  patent  applications  are
denied  and/or some or all of its patents  held  invalid,  the Company  would be
prevented from  precluding its competitors  from using the protected  technology
set forth in such patent applications or patents. Because the Company's products
involve confidential  proprietary  technology and know-how, the Company does not
believe such a loss of patent rights would have a material  adverse  effect upon
the Company.

         The Company also believes that many of its proprietary technologies are
better  protected  as trade  secrets or  copyrights  than by patents.  Moreover,
although  protection  of the  Company's  existing  proprietary  technologies  is
important,  other  factors  such as product  development,  customer  support and
marketing  ability are equally  important to the  development  of the  Company's
business.

         Limited or Single  Sources  of Supply.  The  Company  manufactures  its
scanners at its South San Francisco,  California  facility.  To date the typical
manufacturing cycle has required six months based on inventory and lead time can
be significant between authorization of manufacturing to delivery of a scanner.

         Many of the components and sub-assemblies used in the scanner have been
developed  and  designed  by  Imatron  to  its  custom  specifications  and  are
obtainable  from limited or single sources of supply.  In view of the customized
nature of many of these  components  and  sub-assemblies,  there may be extended
delays between their order and deliver.  Delays in such delivery could adversely
affect Imatron's present and future production  schedules.  The Company has made
and continues to make inventory investments to acquire long lead time components
and  sub-assemblies  to minimize the impact of such delays. In recent years, the
Company has developed  alternative sources for many of its scanner subcomponents
and continues its programs to qualify vendors for the remaining critical parts.

         Also,  certain vendors  currently  require  cash-on-delivery  or prepay
payment  terms.  There can be no assurance  that such actions will not adversely
affect the Company's  production schedule and its ability to deliver products in
a  timely  manner.   As  a  result  of  certain  vendors   currently   requiring
cash-on-delivery  or prepay terms,  the Company must  maintain  higher levels of
cash and other sources of credit to fund material purchases than otherwise would
be required.

         Volatility of Stock Price. The market prices for securities of advanced
technology  companies  have  historically  been highly  volatile,  including the
market price of shares of the Company's  Common Stock.  Future  announcements by
the Company or its competitors, including announcements concerning technological
innovations or new commercial products,  results of clinical testing, changes in
government  regulations,  regulatory  actions,  health care reform,  proprietary
rights,  litigation and public concerns as to the safety of the Company's or its
collaborators'  products,  as well as  period-to-period  variances  in financial
results  could  cause  the  market  price  of  the  Common  Stock  to  fluctuate
substantially.  In addition,  the stock market has experienced extreme price and
volume  fluctuations that have  particularly  affected the market price for many
advanced  technology  companies  that have often been unrelated to the operating

                                       8

<PAGE>

performance of these  companies.  These broad market  fluctuations may adversely
affect the market price of the Common Stock.

         Food  And  Drug  Administration  And  Other  Governmental   Regulation.
Amendments to the Federal Food, Drug, and Cosmetic Act ("Amendments") enacted in
1976, and regulations issued or authorized thereunder, provide for regulation by
the Federal Food and Drug Administration ("FDA") of the marketing,  manufacture,
labeling,  packaging,  sale and distribution of "medical devices," including the
Company's scanner.  Among these regulations are requirements that medical device
manufacturers register their manufacturing facilities with the FDA, list devices
manufactured  by them file  various  reports  and  comply  with  specified  Good
Manufacturing   Practice  ("GMP")  regulations.   The  FDA  enforces  additional
regulations  regarding the safety of equipment  utilizing  x-rays,  including CT
scanners. Various states also impose similar regulations.

         The Amendments also impose certain requirements which must be met prior
to the initial  marketing of medical devices  introduced into commerce after May
28, 1976. Other requirements imposed on medical device  manufacturers  include a
pre-market  notification  process  commonly  known as the 510(k)  application to
market a new or modified  medical  device.  Additionally,  and  specifically  if
required by the FDA, a pre-market approval ("PMA") may be required. This process
is  potentially  expensive  and time  consuming  and must be completed  prior to
marketing a new medical device. The Company has received appropriate  clearances
from the FDA to  market  both the  C-100 and C-150  ULTRAFAST  CT  scanner.  The
Company  believes that it is presently in  substantial  compliance  with the GMP
requirements and other regulatory issues promulgated by the FDA.

         The FDA also regulates the safety and efficacy of radiological devices.
Although  the  Company   believes  it  is  in  compliance  with  all  applicable
radiological  health  regulations  promulgated  by  the  FDA,  there  can  be no
assurance  that the  ULTRAFAST CT scanner will  continue to comply with all such
standards and regulations that may be promulgated. In any event, compliance with
all such  requirements  can be  costly  and  time  consuming,  with a  resultant
materially adverse effect upon the development of the Company's business and its
future profitability.

         FDA  clearance to market does not guarantee or imply  reimbursement  by
third-party payers such as Medicare, Medicaid, Blue Cross/Blue Shield or private
health  insurers.  Medicare  and  Medicaid  reimburse  for  procedures  that are
generally accepted or that have been proven safe and effective.  The Health Care
Financing  Administration ("HCFA"), which oversees Medicare and Medicaid payment
policies,  will not authorize  payment for procedures which are considered to be
experimental.  HCFA has determined that diagnostic  examinations of the head and
other parts of the body  performed by CT scanners are covered if the  contractor
who  administers  the local  Medicare  program finds that medical and scientific
literature  and opinion  support the effective use of a scan for the  particular
condition.

         The Federal government and certain states have enacted cost-containment
measures  such as the  establishment  of maximum fee  standards in an attempt to
limit the extent and cost of  governmental  reimbursement  of allowable  medical
expenses under Medicare, Medicaid and similar governmental programs. A number of
states have adopted or are  considering the adoption of similar  measures.  Such
limitations  have led to a reduction in, and may further  limit 

                                       9

<PAGE>

funds available for, the purchase of diagnostic  equipment such as the Company's
scanner  and in  the  number  of  diagnostic  imaging  procedures  performed  in
hospitals and other medical institutions such as imaging clinics.

         Certain  states have  adopted  requirements  that  hospitals  and other
health care facilities,  such as imaging  clinics,  obtain a Certificate of Need
("CON")  for major  capital  expenditures,  in the absence of which they will be
denied   reimbursement  for  services  and  funding  relating  to  such  capital
expenditures.  A number of states have enacted more  stringent  CON  legislation
such as  requiring  private  physicians  to  obtain  a CON  for any CT  scanner,
regardless of cost. There can be no assurance that Imatron's potential customers
will be able to  secure  CONs or will  be  willing  to  pursue  the  application
procedure.

         The Company's primary customers operate in the healthcare industry. The
health care industry is highly regulated.  Both existing and future governmental
regulations  could  adversely  impact the market for the Company's  ULTRAFAST CT
scanner and the Company's business. The Company's operations are also subject to
regulation by other federal,  state and local governmental entities empowered to
enforce  pertinent  statutes  and  regulations,  such as those  enforced  by the
Occupational  Safety and Health Agency and the Environmental  Protection Agency.
In some  cases,  state or local  regulations  may be stricter  than  regulations
imposed by the federal  government.  The Company was most recently  inspected by
the  State  of  California   Department  of   Occupational   Safety  and  Health
Administration  in November,  1993. Minor violations were issued by Cal/OSHA and
were immediately  corrected by the Company.  The subsequent follow up inspection
in December by the same regulatory body yielded satisfactory results without the
issuance of further  notice of  violation.  The Company  believes  that it is in
substantial compliance with California regulations applicable to its business.

         Competition.  In the non-cardiac imaging  applications market (composed
principally  of  hospital  radiology   departments),   the  Company's  principal
competition is from current manufacturers of conventional CT scanners, including
General Electric Company,  Siemens Corporation,  Elscint,  Picker International,
Inc.,  Philips Medical Systems,  and Toshiba Medical  Corporation.  Non-invasive
diagnostic imaging techniques such as ultrasound,  radioisotope imaging, digital
subtraction  angiography  and  magnetic  resonance  imaging  are also  partially
competitive  with the Company's  scanners,  particularly  in the cardiac imaging
market. Each of the companies named above markets equipment using one or more of
these techniques.  All of these companies have greater  financial  resources and
larger and more established  staffs than those of the Company and their products
are in most cases substantially less expensive than the ULTRAFAST CT scanner.

         The  Company  believes  that  to  compete  successfully  against  these
competitors,  it must  demonstrate  that the  ULTRAFAST  CT  scanner  is both an
acceptable substitute for conventional CT scanners in scanning areas of the body
where motion is not a limitation and a valuable cardiac  diagnostic tool capable
of producing useful images of the heart.  Although the Company believes that the
ULTRAFAST  CT can  produce  images of a  quality  and  resolution  as good as or
superior to images produced by  state-of-the-art  conventional  CT scanners,  it
lacks certain features that many competing premium scanners offer. These include
lack of a high-resolution  mode for imaging the temporal bones and inner ear and
lower functionality in software used for automatically  positioning the patient.
There is no certainty  that potential  purchasers of the Company's  scanner will
accept it without such features.

                                       10

<PAGE>

         Also,  the Company  believes that  customers  and  potential  customers
expect a continuing development effort to improve the functionality and features
of the scanner.  The Company  continually seeks to develop product  enhancements
and improve  product  reliability.  Imatron's  future  success may depend on its
ability to complete certain product enhancement and product reliability projects
currently  in  progress,  as well as on its  continued  ability to  develop  new
products  or  product  enhancements  in  response  to new  products  that may be
introduced by other  companies.  There can be no assurance  that Imatron will be
able to continue to improve product  reliability or introduce new product models
or product enhancements as required to remain competitive.

         Other factors,  in addition to those described above,  that a potential
purchaser  would consider in the decision to replace a  conventional  CT scanner
with  an  ULTRAFAST  CT  scanner  include  purchase  price,  patient  throughput
capacity,  anticipated  operating expenses,  estimated useful life and post-sale
customer  service and support.  The Company believes that its scanner and/or the
Company is competitive with respect to each of these factors.

         Reliance on Distributors.  A substantial portion of the Company's sales
of its scanners is done  through  distributors.  There is no assurance  that the
Company's distributors will actually meet their contractual minimums on a timely
basis.  Failure by the  distributors to meet their  obligations  could adversely
affect the Company.

         No Dividends on Preferred  and Common  Stock.  The Company has not paid
any  dividends on its  Preferred or Common  Stock since  inception.  Even if its
future operations result in revenues and/or profitability, as to which there can
be no assurance,  there is no present  anticipation that dividends will be paid.
Rather,  the Company expects that any future earnings will be applied toward the
further development of the Company's business.

                                 USE OF PROCEEDS

         The Company will not receive any part of the proceeds  from the sale of
the  Shares  by  the  Selling   Shareholders.   As  described   under   "Selling
Shareholders",  a  portion  of the  Shares  will  be  acquired  by  the  Selling
Shareholders upon exercise of the Warrants.  Upon the exercise of a Warrant, the
Company will receive the  applicable  exercise  price per share from the Selling
Shareholder. The Company will use such proceeds to increase working capital.

                                 OFFERING PRICE

         This  Prospectus  may  be  used  from  time  to  time  by  the  Selling
Shareholders who offer the Common Stock registered hereby for sale. The offering
price of such Common Stock will be determined by the Selling Shareholder and may
be based on market price  prevailing at the time of sale, at prices  relating to
such prevailing market prices, or at negotiated  prices. The market price of the
Company's Common Stock on the date of any proposed sale, as listed on the NASDAQ
National Market System, symbol "IMAT", is the most significant but not the only,
factor used to determine the offering price of the Shares.


                                       11
<PAGE>

                              SELLING SHAREHOLDERS

         The following  provides certain  information with respect to the Common
Stock  beneficially  owned by the Selling  Shareholders  who are entitled to use
this  Prospectus.  The  information  in the  table  is as of the  date  of  this
Prospectus. The Common Stock offered by this Prospectus may be offered from time
to time by the Selling Shareholders named below or their nominees:

                             Shares       Shares Available      Percent Owned 
Name of Selling            Beneficially    for Sale Under     After Completion
 Securityholder              Owned(1)      this Prospectus    of the Offering(2)
- ---------------            ------------   ----------------    ------------------

Ambient Capital Group,       102,398          102,398               *
Inc.(3)(4)

Banque Privee Edmond de       69,655           19,200               *
Rothschild, S.A.
Geneva

Forbes W. Burtt(5)             4,516            4,516               *

Michel Cornis                 10,000           10,000               *

Cramer, Rosenthal,             9,600            9,600               *
McGlynn, Inc.

Credit Suisse                 25,600           25,600               *
(Guernsey) Limited

CRM Madison                   38,400           38,400               *
Partners, L.P.

CRM Partners, L.P.           155,200          155,200               *

CRM Retirement                76,800           76,800               *
Partners, L.P.

Elliott Associates,          266,560          266,560               *
L.P.(6)

Joseph P. Galichia,           80,000           80,000               *
M.D.

Global Bermuda Limited       500,000          500,000               *
Partnership

                                       12

<PAGE>

Grace Brothers, Ltd.         180,000          180,000               *

Heritage Finance &             9,032            9,032               *
Trust Company

A.B. Laffer, V.A.              9,600            9,600               *
Canto & Associates

Lakeshore                    104,000          104,000               *
International Ltd.

Lagunitas Partners L.P.       80,000           80,000               *

Libra Investments, Inc.       22,581           22,581               *

Merced Partners              196,000          196,000               *
Limited Partnership

Modern Woodmen                80,000           80,000               *
of America

Robert G. Morrish(5)           2,258            2,258               *

Gary Post(3)                 316,793          316,793               *

Stephen P. Rader              14,400           14,400               *
and Anne W.Rader, 
and their successors,
as trustees of the 
Rader Living Trust 
dated 9/9/94

Ravich Revocable             211,290          211,290               *
Trust of 1989

Reinfrank Living              14,400           14,400               *
Trust UA 6/13/95

SC Fundamental               304,000          304,000               *
Value BVI, Ltd.(7)

SC Fundamental               696,000          696,000               *
Value Fund,L.P.(7)

Jonathan Schwartz(5)           4,516            4,516               *

                                       13

<PAGE>

Mark S. Siegel                 3,360            3,360               *

The Shemano                   35,000           35,000               *
Group, Inc. fbo
Gary J. Shemano(8)

The Shemano                   33,000           33,000               *
Group, Inc. fbo
Michael R. Jacks(8)

The Shemano                    2,000            2,000               *
Group, Inc. fbo
William David 
Corbett & Mary
Corbett Jt. Ten.(8)

Sitrick and                   66,371           66,371               *
Company Inc.(9)

Kathleen Sullivan             28,005            3,840               *

Westgate                     133,440          133,440               *
International, L.P.(6)

All Selling                3,884,775        3,810,155               *
Shareholders as a
Group


- -----------------------------
* Less than 1%

(1)  Includes  shares  owned  prior to this  offering  and the shares  which are
     issuable upon the exercise of the Exchange  Rights and the Warrants held by
     the Selling  Shareholders.  The number of shares  being  offered  hereby is
     shown in the "Shares Available for Sale Under this Prospectus"  column. See
     footnote below.
(2)  Percentages  are based upon the assumption that upon the completion of this
     offering  the  respective  Selling  Shareholder  has sold the Common  Stock
     listed  as  "Shares  Available  for Sale  Under  this  Prospectus"  and are
     computed  on the basis of  76,659,943  shares of Common  Stock  issued  and
     outstanding as of August 23, 1996.
(3)  Ambient  Capital  Group,  Inc.  is 48% owned by Gary Post and he shares the
     power to vote and dispose of the Shares owned by Ambient.
(4)  Ambient Capital Group, Inc. has provided financial  consulting  services to
     the Company and its  subsidiary  HeartScan  Imaging,  Inc. at varying times
     during the past three years.
(5)  Forbes W. Burtt,  Robert G. Morrish and  Jonathan  Schwartz are employed by
     Libra Investments,  Inc., a company which has provided financial consulting
     services to the  Company and  HeartScan  at varying  times  during the past
     three  years.  Jess M.  Ravich  is the  controlling  shareholder  of  Libra
     Investments,  Inc.  and shares the power to vote and  dispose of the Shares
     owned by Libra.
(6)  Paul E. Singer,  either  directly or  indirectly,  may be deemed to control
     each  of  these   entities.   Elliott   Associates,   L.P.   and   Westgate
     International,  L.P. may be deemed to be a group for purposes of Rule 13d-3
     promulgated under the Securities Exchange Act of 1934, as amended.

                                       14

<PAGE>

(7)  Gary  Siegler  and  Peter  Collery  own  controlling  interests  in both SC
     Fundamental  Value BVI, Ltd. And SC Fundamental  Value Fund,  L.P. and each
     individual shares the power to vote and dispose of the Shares owned by such
     Selling Shareholders.
(8)  Gary J. Shemano, Michael R. Jacks and William David Corbett are employed by
     The Shemano Group, Inc., a company which has provided financial  consulting
     services to the  Company and  HeartScan  at varying  times  during the past
     three years.
(9)  Sitrick and Company Inc. has provided public relations  consulting services
     to the Company and HeartScan at varying times during the past two years.

                              PLAN OF DISTRIBUTION

         The Selling  Shareholders  have  advised  the Company  that the Selling
Shareholders  intend to sell their Shares from time to time in private or public
transactions,  in transactions  involving principals,  in transactions involving
brokers,  or by any other lawful  methods.  Sales through brokers may be made by
any method of trading  authorized  by the NASDAQ  National  Market System or any
stock  exchange on which the Shares of Common Stock may be listed in the future,
including  block  trading  in  negotiated  transactions.  Without  limiting  the
foregoing,  such  brokers  may act as  dealers by  purchasing  any or all of the
Shares covered by this Prospectus,  either as agents for others or as principals
for their own accounts and reselling such shares pursuant to this Prospectus. In
sales made through  underwriters,  dealers or brokers, such entities may receive
compensation in the form of underwriting  discounts,  concessions or commissions
from the Selling  Shareholders and/or the purchasers of shares for whom they may
act as agents.

         The Company will pay all of the expenses  incident to the  registration
of the Shares.  The Company will not pay any  expenses  incident to the offering
and sale of the  Common  Stock to the  public,  including,  but not  limited  to
commissions and discounts of underwriters, dealers or agents. 

         The transfer agent for the Common Stock is Continental Stock Transfer &
Trust Co., 2 Broadway, New York, NY 10004.

                                    EXPERTS

         The consolidated  financial statements of Imatron Inc.  incorporated by
reference  in  Imatron  Inc.'s  Annual  Report  (Form  10-K) for the year  ended
December 31, 1995, have been audited by Ernst & Young LLP, independent auditors,
as set forth in their report thereon included therein and incorporated herein by
reference.  Such consolidated  financial  statements are incorporated  herein by
reference in reliance  upon such report given upon the authority of such firm as
experts in accounting and auditing.

                                  LEGAL OPINION

         The legality of the shares of Common Stock  offered will be passed upon
for  the  Company  by  Severson  &  Werson,  A  Professional  Corporation,   One
Embarcadero Center, 26th floor, San Francisco, California 94111.


                                       15

<PAGE>


No  dealer,  salesman  or any  other  person  has  been       3,810,155 Shares  
authorized  to give  any  information  or to  make  any                         
representation  not  contained  in this  Prospectus  in                         
connection  with the  offer  made  hereby.  If given or                         
made, such  information or  representation  must not be                         
relied upon as having been  authorized  by Imatron Inc.                         
This Prospectus does not constitute an offer to sell or         IMATRON INC.    
a solicitation of an offer to buy any securities  other                         
than those  specifically  offered hereby or an offer to      No Par Common Stock
buy to any person in any  jurisdiction in which such an                         
offer or  solicitation  would be unlawful.  Neither the    
delivery of this Prospectus nor any sale made hereunder          PROSPECTUS     
shall under any  circumstances  create any  implication                         
that the information  contained herein is correct as of                         
any time subsequent to the date hereof.                      September 6, 1996
                                                       


                                       16

<PAGE>


                 PART II. INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 14.   Other Expenses of Issuance and Distribution.

         The following  table sets forth all expenses  payable by the Company in
connection  with  the  issuance  and  distribution  of the  Common  Stock  being
registered.1  All the amounts  shown are estimates  except for the  registration
fee.

         Registration fee                                   $ 7,883

         Printing and engraving expenses                        500

         Legal fees and expenses2                             7,500

         Accounting fees and expenses                         3,500

                  Total                                     $19,383

ITEM 15.  Indemnification of Directors and Officers.

         Article IX of the Bylaws of the Company  sets forth the extent to which
officers or directors of the Company may be indemnified  against any liabilities
which they may incur.  The general  effect of such Bylaw  provision  is that any
person made a party to an action,  suit or proceeding by reason of the fact that
he is or was a  director,  officer,  employee  or  agent of the  Company,  or of
another  corporation or other  enterprise which he served as such at the request
of the Company,  shall be indemnified by the Company against expenses (including
attorneys' fees),  judgments,  fines and amounts paid in settlement actually and
reasonably incurred by it in connection with such action, suit or proceeding, to
the full extent permitted under the laws of the State of New Jersey.

         The  general  effect of the  indemnification  provisions  contained  in
Section  14A:3-5 of the New Jersey  General  Corporation  Law is as  follows:  A
director  or officer  who, by reason of such  directorship  or  officership,  is
involved in any  action,  suit or  preceding  (other than an action by or in the
right  of the  Company)  may be  indemnified  by the  Company  against  expenses
(including  attorneys'  fees),  judgments,  fines 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 he  reasonably  believed to
be in or not opposed to the best  interest of the Company,  and, with respect to
any criminal action or proceeding,  had no reasonable  cause to believe that his
conduct was unlawful.  A director or officer who, by reason of such directorship
or  officership,  is  involved  in any  action or suit by or in the right of the
Company may be indemnified by the Company 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

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

1        Blue Sky filings.

2        Including legal expenses associated with Blue Sky filings.

                                       17

<PAGE>

the Company, except that no indemnification may be made in respect of any claim,
issue or  matter  as to which he shall  have  been  adjudged  to be  liable  for
negligence or misconduct in the  performance  of his duty to the Company  unless
and only to the extent that a court of  appropriate  jurisdiction  shall approve
such indemnification.


ITEM 16.  Exhibits.

Exhibit No.  Description
- -----------  -----------

3.1          Certificate  of  Incorporation  of the Company,  as amended,  as of
             March 31, 1983.3

3.2          Certificate of Amendment of Certificate of Incorporation filed with
             the New Jersey Secretary of State on June 7, 1988.4

3.3          Certificate of Amendment of Certificate of Incorporation filed with
             the New Jersey Secretary of State on June 17, 1988.5

3.4          Certificate of Amendment of Certificate of Incorporation filed with
             the New Jersey Secretary of State on July 26, 1988.6

3.5          Certificate   of   Correction  of   Certificate   of  Amendment  of
             Certificate of Incorporation filed with the New Jersey Secretary of
             State on February 7, 1989.7

3.6          Certificate of Amendment of Certificate of Incorporation filed with
             the New Jersey Secretary of State on April 29, 1990.8

- ---------------------
3        Filed as an Exhibit to the Company's Registration Statement on Form S-8
filed  with  the  Commission  on  February  3,  1989  (File  No.  33-26833)  and
incorporated herein by reference.

4        Filed as an Exhibit to the Company's Registration Statement on Form S-8
filed  with  the  Commission  on  February  3,  1989  (File  No.  33-26833)  and
incorporated herein by reference.

5        Filed as an Exhibit to the  Company's  Form 8  amending  the  Company's
Annual  Report on Form 10-K for the fiscal  year ended  December  31, 1988 filed
with the Commission on May 2, 1989 and incorporated herein by reference.

6        Filed as an Exhibit to the Company's Registration Statement on Form S-8
filed  with  the  Commission  on  February  3,  1989  (File  No.  33-26833)  and
incorporated herein by reference.

7        Filed as an Exhibit to the  Company's  Form 8  amending  the  Company's
Annual  Report on Form 10-K for the fiscal  year ended  December  31, 1988 filed
with the Commission on May 2, 1989 and incorporated herein by reference.

8        Filed as an Exhibit to the Company's Annual Report on Form 10-K for the
fiscal year ended December 31, 1989 and incorporated herein by reference.

                                       18

<PAGE>

3.7          Certificate of Amendment of Certificate of Incorporation filed with
             the New Jersey Secretary of State on December 7, 1990.9

3.8          Bylaws, as amended as of April 30, 1992.10

4.1          Common  Stock  Purchase  Agreement  dated June 24, 1996 between the
             Company,  HeartScan  Imaging  Inc.,  and investors in the HeartScan
             Imaging, Inc. Series A Preferred Stock Private Offering.11

4.2          Form of Common Stock  Purchase  Warrant which expires June 24, 2001
             issued to investors in connection with the HeartScan Imaging,  Inc.
             Series A Preferred Stock Private  Offering which concluded June 24,
             1996.

4.3          Form  of  Warrant  Purchase   Agreement  between  the  Company  and
             investors in the Private Offering which concluded June 24, 1996.

4.4          Stock Purchase Agreement between the Company and Gary Post.

4.5          Common Stock Purchase Warrant which expires March 8, 2001 issued to
             Gary Post.

5.1          Opinion  of  Counsel  as  to  the  legality  of  securities   being
             registered.

24.1         Consent of Independent Auditors.

24.2         Consent of Counsel. Reference is made to Exhibit 5.1.

25.1         Power of Attorney (contained in signature pages).

ITEM 17.  Undertakings.

         A.  Rule 415 Offering.

         The undersigned registrant hereby undertakes:

             (1) To file,  during any period in which  offers or sales are being
made, a post-effective amendment to this Registration Statement:

- ---------------------
9        Filed as an Exhibit to the Company's Registration Statement on Form S-8
filed with the  Commission on May 6, 1991 (File No.  33-40391) and  incorporated
herein by reference.

10       Filed as an Exhibit to Post-Effective  Amendment No. 1 to the Company's
Registration  Statement  on Form S-3 filed  with the  Commission  on May 5, 1992
(File No. 33-32218) and incorporated herein by reference.

11       Filed as an Exhibit to the  Company's  Form 8  amending  the  Company's
Annual  Report on Form 10-K for the fiscal  year ended  December  31, 1995 filed
with the Commission on July 1, 1996 and incorporated herein by reference.

                                       19

<PAGE>

                 (i) To include any Prospectus  required by Section  10(a)(3) of
the Securities Act;

                 (ii) To reflect in the  Prospectus  any facts or events arising
after the  effective  date of the  Registration  Statement  (or the most  recent
post-effective  amendment  thereof)  which,  individually  or in the  aggregate,
represent a fundamental  change in the information set forth in the Registration
Statement;

                 (iii) To include any material  information  with respect to the
plan of distribution not previously disclosed in this Registration  Statement or
any material change to such information in the Registration Statement;

         Provided,  however,  that  paragraphs  (A)(1)(i) and  (A)(1)(ii) do not
apply  if the  Registration  Statement  is on Form  S-3,  or Form  S-8,  and the
information  required or to be included in a  post-effective  amendment by those
paragraphs is contained in periodic reports filed by the registrant  pursuant to
Section  13 or  Section  15(d) of the  Exchange  Act that  are  incorporated  by
reference in this Registration Statement.

             (2) That,  for the purpose of determining  any liability  under the
Securities Act, each such  post-effective  amendment 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.

             (3) To  remove  from  registration  by  means  of a  post-effective
amendment  any of the  securities  being  registered  which remain unsold at the
termination of the offering.

             (4) To deliver or cause to be  delivered  with the  Prospectus,  to
each person to whom the Prospectus is sent or given, the latest annual report to
security  holders  that is  incorporated  by  reference  in the  Prospectus  and
furnished  pursuant to and meeting the  requirements of Rule 14a-3 or Rule 14c-3
under the Exchange Act; and, where interim financial  information required to be
presented by Article 3 of Regulation S-X are not set forth in the Prospectus, to
deliver,  or cause to be delivered to each person to whom the Prospectus is sent
or given,  the latest  quarterly  report that is  specifically  incorporated  by
reference in the Prospectus to provide such interim financial information.

         B.  Filings   Incorporating   Subsequent   Exchange  Act  Documents  By
Reference.

         The Company hereby  undertakes  that,  for purposes of determining  any
liability under the Securities  Act, each filing of the Company's  annual report
pursuant  to  Section  13(a)  or  Section  15(d)  of the  Exchange  Act  that is
incorporated by reference in the Registration  Statement shall be deemed to be a
new Registration  Statement relating to the securities offering therein, and the
offering of such  securities at that time shall be deemed to be the initial bona
fide offering thereof.

         C. Acceleration of Effectiveness.

         Insofar as indemnification for liabilities arising under the Securities
Act may be  permitted to  directors,  officers  and  controlling  persons of the
Company pursuant to the foregoing 


                                       20

<PAGE>

provisions,  or  otherwise,  the Company has been advised that in the opinion of
the Securities and Exchange  Commission such  indemnification  is against public
policy as expressed in the Securities Act, and is, therefore,  unenforceable. In
the event that a claim for indemnification  against such liabilities (other than
the payment by the Company of expenses  incurred or paid by a director,  officer
or controlling  person of the Company 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 Company 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  Securities
Act and will be governed by the final adjudication of such issue.


                                       21

<PAGE>

                                   SIGNATURES

         Pursuant  to the  requirements  of the  Securities  Act  of  1933,  the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-3 and has duly caused this Registration
Statement  to be  signed  on its  behalf  by  the  undersigned,  thereunto  duly
authorized,  in the  City of  South  San  Francisco,  State  of  California,  on
September 6, 1996.

                                           IMATRON INC.


                                           By: /s/ S. Lewis Meyer
                                               ---------------------------------
                                                   S. Lewis Meyer
                                           President and Chief Executive Officer


                                       22

<PAGE>

                                POWER OF ATTORNEY

         KNOW ALL PERSONS BY THESE  PRESENTS,  that each person whose  signature
appears below  constitutes  and appoints  Douglas P. Boyd and S. Lewis Meyer, or
either of them,  his true and lawful  attorney-in-fact,  each with full power of
substitution  for him in any and all capacities,  to sign any and all amendments
(including  post-effective  amendments) to this Registration  Statement,  and to
file the same,  with all exhibits  thereto,  and other  documents in  connection
therewith,  with the Securities and Exchange  Commission,  hereby  ratifying and
confirming all that each of said  attorneys-in-fact  or their or his substitutes
or substitute, may do or cause to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, as amended,
this  Registration  Statement  has been signed by the  following  persons in the
capacities and on the dates indicated.

     Signature                     Title                             Date
     ---------                     -----                             ----

/s/ S. LEWIS MEYER          President, Chief Executive         September 6, 1996
- -----------------           Officer and Director
S. Lewis Meyer              


/s/ DOUGLAS P. BOYD         Chairman of the Board              September 6, 1996
- ------------------
Douglas P. Boyd


/s/ GARY H. BROOKS          Vice President Finance, Chief      September 6, 1996
- ---------------------       Financial Officer,
Gary H. Brooks              and Chief Accounting
                            Officer


/s/ JOHN L. COUCH           Director                           September 6, 1996
- --------------------- 
John L. Couch


/s/ TERRY ROSS              Director                           September 6, 1996
- --------------------- 
Terry Ross 


/s/ ALDO TEST               Director                           September 6, 1996
- --------------------- 
Aldo Test


                                       23

<PAGE>

                                  IMATRON INC.

                          INDEX TO EXHIBITS FILED WITH
                         FORM S-3 REGISTRATION STATEMENT

                        3,810,155 Shares of Common Stock


Sequential
Exhibit No.   Description                                               Page No.
- -----------   -----------                                               --------

   4.2        Form of Common Stock Purchase Warrant between the Company    26
              and investors in the Private Offering which concluded 
              June 24, 1996.

   4.3        Form of Warrant Purchase Agreement between the Company       31
              and investors in the Private Offering which concluded 
              June 24, 1996.

   4.4        Stock Purchase Agreement between the Company and Gary        39
              Post dated March 8, 1996.

   4.5        Common Stock Purchase Warrant which expires March 8,         47
              2001 issued to Gary Post.

   5.1        Opinion of Counsel as to legality of securities              54
              being registered.

   24.1       Consent of Ernst & Young LLP, independent auditors.          57

   24.2       Consent of counsel.

              Reference is made to Exhibit 5.1.

   25.1       Power of Attorney (contained in signature pages)


                                       24




                                   Exhibit 4.2






                                       25


<PAGE>

THESE  SECURITIES  HAVE NOT BEEN  REGISTERED  WITH THE  SECURITIES  AND EXCHANGE
COMMISSION UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND ANY SALE, TRANSFER,
PLEDGE OR OTHER DISPOSITION THEREOF MAY BE MADE ONLY (i) IN A REGISTRATION UNDER
SAID ACT OR (ii) IF AN EXEMPTION FROM  REGISTRATION  UNDER SAID ACT IS AVAILABLE
AND THE  COMPANY HAS  RECEIVED  AN OPINION OF COUNSEL TO THAT EFFECT  REASONABLY
SATISFACTORY TO IT.


                                  IMATRON INC.

                          COMMON STOCK PURCHASE WARRANT

                       This Warrant Expires June 24, 2001


Warrant No. IM96-[Warrant Serial No.]                 Shares: [Number of shares]

         THIS CERTIFIES  that,  subject to the terms and  conditions  herein set
forth,  [Name of Warrant  Holder] (the  "Holder")  is entitled to purchase  from
Imatron Inc., a New Jersey corporation (the "Company"), at any time or from time
to time during the Exercise Period (as hereinafter  defined) the number of fully
paid and non-assessable  shares of Common Stock of the Company (the "Shares") as
provided  herein upon surrender  hereof at the principal  office of the Company,
and, at the election of the holder hereof, upon payment of the purchase price at
said office in cash or by cashier's  check or by the wire transfer of funds in a
dollar  amount  equal  to  the  purchase  price  of the  Shares  for  which  the
consideration  is being given.  This  Warrant is issued under and in  accordance
with a Warrant Purchase Agreement (the "Warrant Purchase Agreement") dated as of
June 24, 1996  between  the Company and the Holder,  and is subject to the terms
and provisions contained in the Warrant Purchase Agreement.

         This  Warrant  shall be  exercisable  for that  number of Shares as set
forth above.

         1. Purchase Price. Subject to adjustment as hereinafter  provided,  the
purchase  price of one  share of  Common  Stock  (or such  securities  as may be
substituted for one share of Common Stock pursuant to the provisions hereinafter
set forth) (the "Warrant Price") shall be Six Dollars and Twenty Cents ($6.20).

         2. Adjustment of Warrant Price and Number of Shares. In addition to the
adjustment  provided for in Section 1 above,  the number and kind of  securities
issuable upon the exercise of this Warrant  shall be subject to adjustment  from
time to time upon the happening of certain events as follows:

                  a.  Adjustment for Dividends in Stock.  In case at any time or
from time to time on or after the date hereof the holders of the Common Stock of
the Company (or any shares of stock or other  securities at the time  receivable
upon the  exercise of this  Warrant)  shall have  received,  or, on or after the
record date fixed for the  determination  of eligible  stockholders,  shall have
become entitled to receive,  without payment therefor, other or additional stock
of the Company by way of dividend  (other than as provided for in Paragraph 2(b)
below),  then and in each such case, the holder of this Warrant shall,  upon the
exercise hereof, be entitled to receive,  in addition to the number of shares of
Common  Stock  receivable  thereupon,  and  without  payment  of any  additional
consideration  therefor,  the  amount of such other or  additional  stock of the
Company  which such holder  would hold on the date of such  exercise had it been
the holder of record of such Common Stock on the date hereof and had thereafter,
during  the  period  from  the date  hereof  to and  including  the date of such
exercise,  retained such shares and/or all other  additional stock receivable by
it as aforesaid during such period,  given effect to all adjustments  called for
during such period by this Paragraph 2.

                  b.  Adjustment  for Changes in Common  Stock.  In the event of
changes in the  outstanding  Common Stock of the Company by reason of split-ups,
recapitalizations,  reclassifications,  mergers, consolidations, combinations or
exchanges of shares, separations,  reorganizations,  liquidations,  or the like,
the number and class of shares  available under the Warrant in the aggregate and
the Warrant Price shall be correspondingly adjusted by the Board of Directors of
the Company. The adjustment shall be such as will give the holder of the Warrant
on exercise for the same aggregate  Warrant Price the total number,  class,  and
kind of shares as he would have owned had the Warrant  been  exercised  prior to
the  event  and had he  continued  to hold  such  shares  until  after the event
requiring adjustment.


                                       26

<PAGE>

         3. No Fractional  Shares.  No fractional shares of Common Stock will be
issued in connection with any subscription  hereunder. In lieu of any fractional
shares which would  otherwise be issuable,  the Company  shall pay cash equal to
the product of such fraction multiplied by the fair market value of one share of
Common Stock on the date of exercise,  as determined by the fair market value of
one share of the Company's Common Stock on the date of exercise as determined in
good faith by the Company's Board of Directors.

         4. No Stockholder  Rights. This Warrant shall not entitle its holder to
any of the rights of a stockholder of the Company prior to exercise thereof.

         5. Reservation of Stock.  The Company  covenants that during the period
this Warrant is  exercisable,  the Company will reserve from its  authorized and
unissued Common Stock a sufficient  number of shares to provide for the issuance
of Common Stock upon the exercise of this Warrant.  The Company  agrees that its
issuance of this Warrant shall constitute full authority to its officers who are
charged with the duty of executing  stock  certificates to execute and issue the
necessary  certificates  for shares of Common  Stock upon the  exercise  of this
Warrant.

         6. Exercise of Warrant. This Warrant may be exercised by the registered
holder or its registered  assigns, in whole or in part, by the surrender of this
Warrant  at the  principal  office  of the  Company,  together  with the form of
subscription hereof duly executed,  accompanied by payment in full of the amount
of the  Warrant  Price in the  form  described  in this  Warrant.  Upon  partial
exercise  hereof,  a new  warrant  or  warrants  containing  the  same  date and
provisions  as this  Warrant  shall be issued by the  Company to the  registered
holder  for the  number of shares of Common  Stock  with  respect  to which this
Warrant  shall not have been  exercised.  A Warrant shall be deemed to have been
exercised  immediately  prior  to the  close  of  business  on the  date  of its
surrender for exercise as provided above, and the person entitled to receive the
shares of Common  Stock  issuable  upon such  exercise  shall be treated for all
purposes  as the holder of such  shares of record as of the close of business on
such date. As promptly as  practicable  on or after such date, the Company shall
issue and  deliver to the  person or persons  entitled  to receive  the same,  a
certificate  or  certificates  for the  number of full  shares  of Common  Stock
issuable  upon such  exercise,  together  with cash in lieu of any fraction of a
share as provided above.

         7. Certificate of Adjustment. Whenever the Warrant Price is adjusted as
herein provided, the Company shall promptly deliver to the record holder of this
Warrant a  certificate  of an officer of the Company  setting forth the relevant
Warrant  Price or number of shares  after such  adjustment  and setting  forth a
brief statement of the facts requiring such adjustment.

         8.  Compliance  With  Securities  Act. The holder of this  Warrant,  by
acceptance hereof, agrees that this Warrant and the shares of Common Stock to be
issued upon  exercise  hereof (or shares of any security  into which such Common
Stock may be converted)  are being  acquired for  investment and that the holder
will not offer,  sell,  or  otherwise  dispose of this Warrant and any shares of
Common Stock to be issued upon  exercise  hereof (or shares of any security into
which such Common Stock may be converted) except under  circumstances which will
not result in a violation of the Securities Act of 1933, as amended (the "Act").
Upon  exercise of this Warrant,  the holder  hereof  shall,  if requested by the
Company,  confirm  in writing  its  investment  purpose  and  acceptance  of the
restrictions on transfer of the shares of Common Stock.

         9. Subdivision of Warrant. At the request of the holder of this Warrant
in  connection  with a transfer or exercise  of a portion of the  Warrant,  upon
surrender of such  Warrant for such  purpose to the Company,  the Company at its
expense  (except for any transfer tax payable) will issue and exchange  therefor
warrants  of like  tenor and date  representing  in the  aggregate  the right to
purchase  such number of shares of such Common Stock as shall be  designated  by
such holder at the time of such surrender; provided, however, that the Company's
obligations to subdivide  securities  under this section shall be subject to and
conditioned  upon the compliance of any such  subdivision  with applicable state
securities laws and with the Act.


                                       27


<PAGE>


         10.      Notices of Record Date.  In case

                  (a) the  Company  shall  take a record of the  holders  of its
         Common Stock (or other stock or securities at the time  receivable upon
         the  exercise  of the  Warrant)  for the purpose of  entitling  them to
         receive any dividend or other distribution,  or any rights to subscribe
         for or  purchase  any  shares  of  stock  of  any  class  or any  other
         securities, or to receive any other right, or

                  (b)  of  any  capital   reorganization  of  the  Company,  any
         reclassification of the capital stock of the Company, any consolidation
         or merger  of the  Company  with or into  another  corporation,  or any
         conveyance of all or substantially  all of the assets of the Company to
         another corporation, or

                  (c) of any voluntary dissolution, liquidation or winding-up of
         the Company,

then, and in each such case, the Company will mail or cause to be mailed to each
holder of a Warrant at the time outstanding a notice specifying, as the case may
be,  (i) the date on  which a record  is to be  taken  for the  purpose  of such
dividend,  distribution  or right,  and stating the amount and character of such
dividend,  distribution or right, or (ii) the date on which such reorganization,
reclassification, consolidation, merger, conveyance, dissolution, liquidation or
winding-up is to take place,  and the time,  if any is to be fixed,  as of which
the holders of record of Common Stock or such other stock or  securities  at the
time  receivable  upon the exercise of the Warrant shall be entitled to exchange
their shares of Common Stock (or such other stock or securities)  for securities
or  other  property  deliverable  upon  such  reorganization,  reclassification,
consolidation,  merger, conveyance, dissolution, liquidation or winding-up. Such
notice shall be mailed at least 30 days prior to the date therein specified.

         11. Loss, Theft, Destruction, or Mutilation of Warrant. Upon receipt by
the  Company  of  evidence  reasonably  satisfactory  to it of the loss,  theft,
destruction,  or  mutilation  of this Warrant,  and in case of loss,  theft,  or
destruction,  of indemnity or security  reasonably  satisfactory to it, and upon
reimbursement to the Company of all reasonable expenses incidental thereto,  and
upon surrender and cancellation of this Warrant, if mutilated,  the Company will
make and deliver a new Warrant of like tenor and dates as of such  cancellation,
in lieu of this Warrant.

         12.  Miscellaneous.  This Warrant  shall be governed by the laws of the
State  of  California.  The  headings  in  this  Warrant  are  for  purposes  of
convenience  and  reference  only,  and shall not be deemed to constitute a part
hereof.  Neither  this  Warrant  nor any term  hereof  may be  changed,  waived,
discharged,  or terminated orally but only by an instrument in writing signed by
the  Company  and  the  registered   holder   hereof.   All  notices  and  other
communications  from the  Company  to the  holder  of this  Warrant  shall be by
telecopy or expedited courier service to the address furnished to the Company in
writing by the last holder of this  Warrant who shall have  furnished an address
to the Company in writing.

         13.  Exercise  Period.  The  Exercise  Period  shall  mean  the  period
commencing on the date hereof and ending on June 24, 2001.

         ISSUED this 24th day of June, 1996.

                                  IMATRON INC.


                                  By_________________________
                                        Vice President

                                     [Seal]

                                       28

<PAGE>

                              IMATRON INC. FORM S-3

                             Schedule to Exhibit 4.2
                    Pursuant to Instruction No. 2 to Item 601
                                of Regulation S-K

         The form of Common Stock Purchase  Warrant filed as Exhibit 4.2 to this
Registration  Statement is substantially  identical in all material  respects to
each of the Common Stock Purchase Warrants issued by the Company to investors in
connection  with the HeartScan  Imaging,  Inc.  Series A Preferred Stock Private
Offering  conducted by the Company which  concluded June 24, 1996. This Schedule
relates to each  Warrant  for those  investors  whose  Warrant  Shares are being
registered for sale by this Registration Statement.  The Schedule sets forth the
material  details of all such  warrants  which  differ  from the form of exhibit
filed herewith.

Name of Warrantholder                        Number of Common Shares Exercisable
- ---------------------                        -----------------------------------

Ambient Capital Group, Inc.                            14,678

Forbes W. Burtt                                         4,516

Heritage Finance & Trust Company                        9,032

Libra Investments, Inc.                                22,581

Robert G. Morrish                                       2,258

Gary Post                                              44,033

Ravich Revocable Trust of 1989                         11,290

Jonathan Schwartz                                       4,516

The Shemano Group, Inc. fbo William David               2,000
Corbett & Mary Corbett, Jt. Ten.

The Shemano Group, Inc. fbo Michael R.                 33,000
Jacks

The Shemano Group, Inc. fbo Gary J.                    35,000
Shemano


                                       29




                                   Exhibit 4.3





                                       30

<PAGE>


                           WARRANT PURCHASE AGREEMENT


         THIS WARRANT PURCHASE  AGREEMENT (the  "Agreement") is made and entered
into this 24th day of June,  1996 by and  between  IMATRON  INC.,  a New  Jersey
corporation  (the  "Company")  and  [Name  of  Investor],   a  corporation  (the
"Investor").

                                R E C I T A L S:

     WHEREAS,  the Company desires to issue to Investor and the Investor desires
to purchase from the Company a warrant (the  "Warrant")  to purchase  [Number of
Shares] shares of the Company's common stock (the "Shares") all on the terms and
conditions  hereinafter  provided.  The  Warrant  and the Shares  are  hereafter
collectively referred to as the "Securities".

     NOW, THEREFORE, IT IS AGREED AS FOLLOWS:

     1. Issuance of Warrant. For good and valuable consideration the receipt and
sufficiency of which is acknowledged by the Company, the Company agrees to issue
to Investor the Warrant, the form of which is attached hereto as Exhibit A.

     2. Investor Representations. Investor hereby represents and warrants to the
Company as follows:

          (a) The  Investor  understands  that:  (a) The  offer  and sale of the
Securities  by the  Company  to  Investor  has not  been  registered  under  the
Securities Act of 1933 (the "Securities  Act"), in reliance on an exemption from
such  registration   available  under  the  Securities  Act  and  rules  adopted
thereunder;  (b) The  Investor  must hold the  Warrant  indefinitely  unless the
Securities are  subsequently  registered  under the Securities Act and qualified
under  applicable  state  securities  laws,  or  unless an  exemption  from such
registration and qualification is available.

          (b)  The  Investor  is  acquiring  the  Securities  for his or her own
account, for investment,  and not with a view to any sale or distribution of any
interest therein.

          (c) The Investor has such  knowledge  and  experience in financial and
business  matters  as to be  capable  of  evaluating  the merits and risks of an
investment  in the  Securities,  and the  Investor is able to bear the  economic
risks of such an investment.

          (d) All statements made, and information furnished, by the Investor in
this  certificate  and all other  information  furnished  by the Investor to the
Company, are true and complete, to the best of the Investor's knowledge.

     3.   Restrictions on Transfer.  The Investor agrees that:

          (a) The  Investor  will not  attempt to  transfer  the  Securities  in
violation of the restrictions set forth in this Agreement.

          (b) The Company may note such  restrictions on transfer in its records
and refuse to recognize any transfer  which violates this agreement or for which
the Company has not received an acceptable  opinion of counsel stating that such
transfer will not violate such restrictions.

          (c) One or more legends  indicating a lack of  registration  under the
Securities Act and a lack of  qualification  under state securities laws will be
imprinted  on the  Securities.  One such  legend  shall  read  substantially  as
follows:


                                       31

<PAGE>

     THE SECURITIES  HAVE NOT BEEN  REGISTERED  WITH THE SECURITIES AND EXCHANGE
COMMISSION UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND ANY SALE, TRANSFER,
PLEDGE OR OTHER DISPOSITION THEREOF MAY BE MADE ONLY (i) IN A REGISTRATION UNDER
SAID ACT OR (ii) IF AN EXEMPTION FROM  REGISTRATION  UNDER SAID ACT IS AVAILABLE
AND THE  COMPANY HAS  RECEIVED  AN OPINION OF COUNSEL TO THAT EFFECT  REASONABLY
SATISFACTORY TO IT.

     4. Binding on  Successors;  Indemnification.  The Investor  agrees that the
above  representations  and warranties are binding on the Investor's  successors
and assigns  and are made for the  benefit of the Company and any other  persons
who may become liable for  violations of federal or state  securities  laws as a
result of the falsity of any of the  Investor's  representations  or warranties.
The Investor  agrees to indemnify,  defend,  and hold harmless such persons from
any liability arising from the falsity of any of the Investor's  representations
or warranties or from the breach of any covenant of Investor contained herein.

     5. Registration Rights. The Company hereby grants to Investor the following
registration rights with respect to the Shares:

          (a) Definitions.

          "Commission" shall mean the Securities and Exchange  Commission or any
other federal agency at the time  administering  the Securities Act of 1933 (the
"Securities Act").

          "Register,"  "registered," and "registration"  refer to a registration
effected by preparing and filing a registration statement in compliance with the
Securities Act of 1933, and the declaration or ordering of the  effectiveness of
such registration statement.

          "Registration  Expenses"  shall  mean  all  expenses  incurred  by the
Company in compliance with the provisions of this Section 5, including,  without
limitation,  all  registration  and filing  fees,  printing  expenses,  fees and
disbursements  of counsel for the Company,  blue sky fees and expenses,  and the
expenses of any special audits incident to or required by any such  registration
(but excluding the compensation of regular employees of the Company, which shall
be paid in any event by the Company).

          "Selling  Expenses" shall mean all underwriting  discounts and selling
commissions  applicable to the sale of Shares and all fees and  disbursements of
counsel to Investor.

          "Shares"  means the shares of the Company's  common stock  exercisable
upon  exercise of the Warrant and any common stock  issued with respect  thereto
(e.g. upon a stock split or stock dividend.

          "Investor"  means  the  person  set  forth  above  and  any  permitted
assignee.

          (b) Company Registration.

               i) Notice of  Registration.  If, at any time after June 30, 1996,
the Company shall determine to register any of its securities either for its own
account  or the  account  of a  security  holder  or  holders  exercising  their
respective demand registration rights, other than a registration relating solely
to employee  benefit plans,  or a registration  relating  solely to a Commission
Rule 145 transaction,  or a registration on any registration form which does not
permit secondary sales, the Company will:

                    a) promptly give to Investor  written  notice thereof (which
shall  include a list of the  jurisdictions  in which  the  Company  intends  to
attempt to qualify such securities  under the applicable blue sky or other state
securities laws); and

                    b)   include   in  such   registration   (and  any   related
qualification under blue sky laws or other compliance),  and in any underwriting
involved  therein,  all the Shares  specified in a written  request or requests,
made by Investor  within  fifteen (15) days after receipt of the written  notice
from the Company  described  in this clause (i),  except as set forth in Section
5(b)(ii) below.

                                       32

<PAGE>

               ii) Underwriting.  If the registration of which the Company gives
notice is for a  registered  public  offering  involving  an  underwriting:  the
Company shall so advise Investor as part of the written notice given pursuant to
Section  5(b)  hereof.  In such event,  the right of  Investor  to  registration
pursuant to this Section 5 shall be conditioned upon Investor's participation in
such  underwriting and the inclusion of Investor's Shares in the underwriting to
the extent  provided  herein.  Investor shall  (together  with the Company,  its
directors and officers, and any other shareholders distributing their securities
through such  underwriting)  enter into an  underwriting  agreement in customary
form with the  underwriter  or  underwriters  selected for  underwriting  by the
Company.

     Notwithstanding  any other  provision of this Section 5, if the underwriter
determines  that marketing  factors require a limitation on the number of shares
to be  underwritten,  the  underwriter  may exclude from such  registration  and
underwriting  some or all of the Shares which would  otherwise  be  underwritten
pursuant hereto.  Any securities so excluded shall be apportioned pro rata among
Investor and any other  shareholders  distributing their securities through such
underwriting  according to the total amount of securities  otherwise entitled to
be included therein owned by such  shareholders or in such other  proportions as
shall mutually be agreed upon.

     If Investor disapproves of the terms of any such underwriting, it may elect
to withdraw therefrom by written notice to the Company and the underwriter.  Any
Shares excluded or withdrawn from such underwriting shall be withdrawn from such
registration.

     The Company  shall bear all  Registration  Expenses  incurred in connection
with any  registration,  qualification and compliance by the Company pursuant to
this  Section  5. All  Selling  Expenses  shall be borne by the  holders  of the
securities so registered  pro rata on the basis of the number of their shares so
registered.

               iii)  Registration  Procedures.   In  the  case  of  registration
effected  by the  Company  pursuant to this  Agreement,  the  Company  will keep
Investor  advised in writing as to the initiation of registration  and as to the
completion thereof. At its expense, the Company will:

                    a) keep such registration effective for a period of one year
or until Investor has completed the  distribution  described in the registration
statement relating thereto, whichever first occurs;

                    b) furnish such number of  prospectuses  and other documents
incident thereto as Investor from time to time may reasonably request; and

                    c) use its best  efforts to  register  or qualify the Shares
under the  securities  or blue sky laws of such  jurisdictions  as Investor  may
request; provided,  however, that the Company shall not be obligated to register
or qualify such Shares in any particular jurisdiction in which the Company would
be  required  to  execute a general  consent  to  service of process in order to
effect such registration,  qualification,  or compliance,  unless the Company is
already subject to service in such jurisdiction and except as may be required by
the Securities Act or applicable rules or regulations thereunder.

                    d) Notify the holder of Shares covered by such  registration
statement  at any time when a  prospectus  relating  thereto is  required  to be
delivered  under the Act of the  happening of any event as a result of which the
prospectus included in such registration  statement, as then in effect, includes
an  untrue  statement  of a  material  fact or omits to  state a  material  fact
required to be stated  therein or necessary to make the  statements  therein not
misleading in the light of the circumstances then existing.


          (c) Indemnification.

               i) The Company will indemnify the Investor, each of its officers,
directors and partners,  and each person  controlling  such Investor  within the
meaning of Section 15 of the  Securities  Act or the 1934 Act,  with  respect to
which  registration,  qualification or compliance has been effected  pursuant to
this Agreement,  and each underwriter,  if any, and each person who controls any
underwriter  within the meaning of Section 15 of the  Securities Act or the 1934
Act, against all expenses, claims, losses, damages or liabilities (or actions in
respect thereof),  including any of the foregoing  incurred in settlement of any
litigation,  commenced  or  threatened,  arising  out of or based

                                       33

<PAGE>

on any untrue  statement  (or  alleged  untrue  statement)  of a  material  fact
contained in any registration statement,  prospectus, offering circular or other
document,  or  any  amendment  or  supplement  thereto,  incident  to  any  such
registration,  qualification or compliance, or based on any omission (or alleged
omission)  to state  therein a material  fact  required to be stated  therein or
necessary to make the statements  therein,  in the light of the circumstances in
which they were made,  not  misleading,  or any  violation by the Company of the
Securities Act, or the 1934 Act, or any rule or regulation promulgated under the
Securities  Act,  or the 1934 Act,  or under any state  securities  law or under
common law,  applicable to the Company in connection with any such registration,
qualification or compliance,  and the Company will reimburse the Investor,  each
of its  officers,  directors  and  partners,  and each  person  controlling  the
Investor,   each  such  underwriter  and  each  person  who  controls  any  such
underwriter,  for any legal and any other expenses reasonably incurred,  as such
expenses are incurred, in connection with investigating,  preparing or defending
any such claim, loss, damage, liability or action;  provided,  however, that the
Company will not be liable (i) for amounts paid in  settlement of any such loss,
claim,  damage,  liability or action if such settlement is effected  without the
consent of the Company  (which consent shall not be  unreasonably  withheld) and
(ii) in any such case to the extent that any such claim, loss, damage, liability
or expense  arises out of or is based on any untrue  statement  or  omission  or
alleged  untrue  statement or omission,  made in reliance upon and in conformity
with written information furnished to the Company by an instrument duly executed
by the Investor, controlling person or underwriter and stated to be specifically
for use therein.

               ii)  The  Investor  will,  if  Shares  held by the  Investor  are
included  in the  securities  as to which such  registration,  qualification  or
compliance is being effected,  indemnify the Company,  each of its directors and
officers, each underwriter,  if any, of the Company's securities covered by such
a  registration  statement,  each  person  who  controls  the  Company  or  such
underwriter  within the meaning of Section 15 of the  Securities Act against all
claims,  losses, damages and liabilities (or actions in respect thereof) arising
out of or based on any untrue  statement  (or  alleged  untrue  statement)  of a
material fact contained in any such registration statement, prospectus, offering
circular or other  document,  or any  omission  (or alleged  omission)  to state
therein a material fact  required to be stated  therein or necessary to make the
statements  therein  not  misleading,  and  will  reimburse  the  Company,  such
directors,  officers, persons,  underwriters or control persons for any legal or
any other  expenses  reasonably  incurred in connection  with  investigating  or
defending any such claim, loss, damage, liability or action, in each case to the
extent,  but only to the extent,  that such untrue  statement (or alleged untrue
statement)  or  omission  (or  alleged  omission)  is made in such  registration
statement,  prospectus, offering circular or other document in reliance upon and
in conformity with written information furnished to the Company by an instrument
duly  executed by the  Investor and stated to be  specifically  for use therein.
Notwithstanding  the  foregoing,  the  liability  of  the  Investor  under  this
subsection  shall not apply to  amounts  paid in  settlement  of any such  loss,
claim,  damage,  liability or action if such settlement is effected  without the
consent of the Investor (which consent shall not be unreasonably withheld),  and
(ii) shall be limited in an amount  equal to the  aggregate  net proceeds of the
shares sold by the Investor,  except to the extent such liability  arises out of
or is based on willful misconduct by the Investor.

               iii) Each party  entitled to  indemnification  under this Section
5(c) (the  "Indemnified  Party")  shall  give  notice to the party  required  to
provide   indemnification   (the  "Indemnifying   Party")  promptly  after  such
Indemnified Party has actual knowledge of any claim as to which indemnity may be
sought,  and shall  permit the  Indemnifying  Party to assume the defense of any
such claim or any litigation resulting therefrom,  provided that counsel for the
Indemnifying  Party,  who shall conduct the defense of such claim or litigation,
shall  be  approved  by  the   Indemnified   Party  (whose  approval  shall  not
unreasonably  be withheld),  and the  Indemnified  Party may participate in such
defense at such party's  expense,  and provided  further that the failure of any
Indemnified  Party to give  notice as  provided  herein  shall not  relieve  the
Indemnifying  Party of its obligations under this Agreement except to the extent
that  the  failure  to  give  such  notice  is  materially   prejudicial  to  an
Indemnifying  Party's ability to defend such action and provided  further,  that
the  Indemnifying  Party  shall not assume the  defense  for matters as to which
there is a conflict of interest or separate and  different  defenses,  but shall
pay the fees and expenses of one separate  counsel  retained by the  Indemnified
Party in the event of such conflict of interest.  No Indemnifying  Party, in the
defense of any such claim or litigation,  shall, except with the consent of each
Indemnified Party, consent to entry of any judgment or enter into any settlement
which  does not  include  as an  unconditional  term  thereof  the giving by the
claimant or plaintiff to such Indemnified  Party of a release from all liability
in respect to such claim or litigation.

               iv) If the  indemnification  provided for in this Section 5(c) is
held by a court of competent  jurisdiction  to be  unavailable to an indemnified
party with respect to any loss, liability, claim, damage, or expense referred to
therein,  then the Indemnifying  Party, in lieu of indemnifying such Indemnified
Party  hereunder,  shall  contribute  to the  amount  paid  or  payable  by such
Indemnified Party as a result of such loss, liability, claim, 

                                       34

<PAGE>

damage,  or expense in such proportion as is appropriate to reflect the relative
fault of the Indemnifying  Party on the one hand and of the Indemnified Party on
the other in connection  with the  statements or omissions that resulted in such
loss,  liability,  claim,  damage,  or  expense  as well as any  other  relevant
equitable  considerations.  The relative fault of the Indemnifying  Party and of
the  Indemnified  Party shall be determined by reference to, among other things,
whether  the  untrue or  alleged  untrue  statement  of a  material  fact or the
omission  to state a  material  fact  relates  to  information  supplied  by the
indemnifying party or by the indemnified party and the parties' relative intent,
knowledge,  access to  information,  and  opportunity to correct or prevent such
statement or omission.

               v) The  obligations  of the Company and the  Investor  under this
Section  5(c)  shall  survive  the  completion  of any  offering  of Shares in a
registration statement under this Section 5 and otherwise.

               vi)  Information by Investor.  The Investor of Shares included in
any  registration  shall  furnish  to the  Company  such  information  regarding
Investor,  the Shares held by it and the distribution  proposed by such Investor
as the Company  may  reasonably  request in writing  and as shall be  reasonably
required  in  connection  with any  registration,  qualification  or  compliance
referred to in this Agreement.

               vii)  Transfer of  Registration  Rights.  The rights to cause the
Company to register  securities  granted Holders under Section 5 may be assigned
to a transferee  or assignee in  connection  with any transfer or  assignment of
Shares by a Holder provided that: (i) such transfer may otherwise be effected in
accordance with applicable  securities laws and (ii) such assignee or transferee
becomes a party to this  Agreement  and  assumes all of the  obligations  of the
transferring Holder under Section 5.

     6. Rule 144  Reporting.  With a view to making  available  the  benefits of
certain rules and regulations of the Commission which may at any time permit the
sale of the Shares to the public without registration, Imatron agrees to use its
best efforts to:

          (a) Make and keep  public  information  available,  as those terms are
understood and defined in Rule 144 under the Securities  Act, at all times after
the effective date that Imatron becomes subject to the reporting requirements of
the Securities Act or the Securities Exchange Act of 1934, as amended.

          (b) File with the  Commission in a timely manner all reports and other
documents  required  of  Imatron  under the  Securities  Act and the  Securities
Exchange  Act of 1934,  as amended  (at any time after it has become  subject to
such reporting requirements); and

          (c) So long as Investor  owns any Shares,  to furnish to the Purchaser
forthwith upon request a written  statement by Imatron as to its compliance with
the reporting  requirements of said Rule 144 (at any time after ninety (90) days
after the effective date of the first  registration  statement  filed by Imatron
for an offering of its securities to the general public),  and of the Securities
Act and the  Securities  Exchange  Act of 1934 (at any time  after it has become
subject to such  reporting  requirements),  a copy of the most recent  annual or
quarterly report of the Company, and such other reports and documents of Imatron
and other  information in the possession of or reasonably  obtainable by Imatron
as a  Shareholder  may  reasonably  request  in  availing  itself of any rule or
regulation of the Commission  allowing a Shareholder to sell any such securities
without registration.

     7.  Governing  Law.  This  Agreement  shall be governed by and construed in
accordance with the laws of the State of California.

     8.  Counterparts.   This  Agreement  may  be  executed  in  any  number  of
counterparts,  each of which  shall be an  original,  but all of which  together
shall constitute one instrument.


                                       35

<PAGE>

     IN WITNESS  WHEREOF,  the  undersigned  purchasers  of  securities  and the
Company have executed this Agreement as of the day and year first above written.


                                    COMPANY:

                                             IMATRON INC.

                                             By:___________________________
                                                     Vice President


                                    INVESTOR:

                                             [Name of Investor]


                                             By:___________________________
                                             Its___________________________


                                       36




                              IMATRON INC. FORM S-3

                             Schedule to Exhibit 4.3
                    Pursuant to Instruction No. 2 to Item 601
                                of Regulation S-K

         The form of Warrant  Purchase  Agreement  filed as Exhibit  4.3 to this
Registration  Statement is substantially  identical in all material  respects to
each of the Warrant Purchase Agreements between the Company and investors in the
HeartScan  Imaging,  Inc. Series A Preferred Stock Private Offering conducted by
the Company which concluded June 24, 1996. This Schedule relates to each Warrant
Purchase Agreement for those investors whose Warrant Shares are being registered
for sale by this  Registration  Statement.  The Schedule sets forth the material
details of all such agreements which differ from the exhibit filed herewith.

Name of  Warrantholder                       Number of Common Shares Exercisable
- ----------------------                       -----------------------------------

Ambient Capital Group, Inc.                                14,677

Forbes W. Burtt                                             4,516

Heritage Finance & Trust Company                            9,032

Libra Investments, Inc.                                    22,581

Robert G. Morrish                                           2,258

Gary Post                                                  44,033

Ravich Revocable Trust of 1989                             11,290

Jonathan Schwartz                                           4,516

The Shemano Group, Inc. fbo William David                   2,000
Corbett & Mary Corbett, Jt. Ten.

The Shemano Group, Inc. fbo Michael R.                     33,000
Jacks

The Shemano Group, Inc. fbo Gary J.                        35,000
Shemano



                                       37




                                   Exhibit 4.4




                                       38

<PAGE>

                            STOCK PURCHASE AGREEMENT


     THIS STOCK PURCHASE  AGREEMENT (the  "Agreement")  is made and entered into
this  8th  day of  March,  1996  by  and  between  IMATRON  INC.,  a New  Jersey
corporation (the "Company") and GARY POST (the "Investor").

                                R E C I T A L S:

     WHEREAS, the Investor has performed certain investment banking services for
the Company and has earned and been paid fees in connection  with such services;
and

     WHEREAS,  the  Company has agreed to permit the  Investor to exchange  such
fees for ("Units"),  each unit  consisting of one share of its Common Stock (the
"Common  Stock") and five common stock purchase  warrants to purchase  shares of
Common Stock at $1.71 per share (the "Warrants"). The Warrant and the Shares are
hereafter collectively referred to as the "Securities";

     WHEREAS,  the Purchaser desires to purchase and the Company desires to sell
the Units on the terms and conditions set forth herein.

     NOW, THEREFORE, IT IS AGREED AS FOLLOWS:

     1. Purchase and Sale of Units.  The Company agrees to sell to the Purchaser
and upon the basis of the  representations  and  warranties,  and subject to the
terms and  conditions,  set forth in this  Agreement,  the  Purchaser  agrees to
purchase 43,860 Units ("Units") at $1.71 per Unit or an Aggregate Purchase Price
of $75,000.

     2. Closing.  The closing of the purchase and sale of the Units  pursuant to
Section 1 hereof  shall  take  place on such  date as may be agreed  upon by the
parties  (the  "Closing  Date")  at a time and  place to be  agreed  upon by the
parties.  The  certificates  representing  the  Units  to be  purchased  by  the
Purchaser  shall be delivered by, or on behalf of, the Company and the Purchaser
shall deliver  payment of the Aggregate  Purchase  Price therefor in immediately
available funds to the Company's account by wire transfer or by check.

     3. Investor Representations. Investor hereby represents and warrants to the
Company as follows:

          (a) The  Investor  understands  that:  (a) The  offer  and sale of the
Securities  by the  Company  to  Investor  has not  been  registered  under  the
Securities Act of 1933 (the "Securities  Act"), in reliance on an exemption from
such  registration   available  under  the  Securities  Act  and  rules  adopted
thereunder;  (b) The  Investor  must hold the  Warrant  indefinitely  unless the
Securities are  subsequently  registered  under the Securities Act and qualified
under  applicable  state  securities  laws,  or  unless an  exemption  from such
registration and qualification is available.

          (b)  The  Investor  is  acquiring  the  Securities  for his or her own
account, for investment,  and not with a view to any sale or distribution of any
interest therein.

                                       39


<PAGE>

          (c) The Investor has such  knowledge  and  experience in financial and
business  matters  as to be  capable  of  evaluating  the merits and risks of an
investment  in the  Securities,  and the  Investor is able to bear the  economic
risks of such an investment.

          (d) All statements made, and information furnished, by the Investor in
this  certificate  and all other  information  furnished  by the Investor to the
Company, are true and complete, to the best of the Investor's knowledge.

     4. Restrictions on Transfer. The Investor agrees that:

          (a) The  Investor  will not  attempt to  transfer  the  Securities  in
violation of the restrictions set forth in this Agreement.

          (b) The Company may note such  restrictions on transfer in its records
and refuse to recognize any transfer  which violates this agreement or for which
the Company has not received an acceptable  opinion of counsel stating that such
transfer will not violate such restrictions.

          (c) One or more legends  indicating a lack of  registration  under the
Securities Act and a lack of  qualification  under state securities laws will be
imprinted  on the  Securities.  One such  legend  shall  read  substantially  as
follows:

         THE  SECURITIES  HAVE  NOT BEEN  REGISTERED  WITH  THE  SECURITIES  AND
         EXCHANGE  COMMISSION UNDER THE SECURITIES ACT OF 1933, AS AMENDED,  AND
         ANY SALE,  TRANSFER,  PLEDGE OR OTHER  DISPOSITION  THEREOF MAY BE MADE
         ONLY (i) IN A REGISTRATION  UNDER SAID ACT OR (ii) IF AN EXEMPTION FROM
         REGISTRATION  UNDER SAID ACT IS AVAILABLE  AND THE COMPANY HAS RECEIVED
         AN OPINION OF COUNSEL TO THAT EFFECT REASONABLY SATISFACTORY TO IT.

     5. Binding on  Successors;  Indemnification.  The Investor  agrees that the
above  representations  and warranties are binding on the Investor's  successors
and assigns  and are made for the  benefit of the Company and any other  persons
who may become liable for  violations of federal or state  securities  laws as a
result of the falsity of any of the  Investor's  representations  or warranties.
The Investor  agrees to indemnify,  defend,  and hold harmless such persons from
any liability arising from the falsity of any of the Investor's  representations
or warranties or from the breach of any covenant of Investor contained herein.

     6. Registration Rights. The Company hereby grants to Investor the following
registration rights with respect to the Shares:

          (a) Definitions.

          "Commission" shall mean the Securities and Exchange  Commission or any
other federal agency at the time  administering  the Securities Act of 1933 (the
"Securities Act").

          "Register,"  "registered," and "registration"  refer to a registration
effected by preparing and filing a registration statement in compliance with the
Securities Act of 1933, and the

                                       40

<PAGE>

declaration or ordering of the effectiveness of such registration statement.

          "Registration  Expenses"  shall  mean  all  expenses  incurred  by the
Company in compliance with the provisions of Sections 2 and 3 hereof, including,
without limitation,  all registration and filing fees,  printing expenses,  fees
and  disbursements of counsel for the Company,  blue sky fees and expenses,  and
the  expenses  of any  special  audits  incident  to or  required  by  any  such
registration  (but  excluding  the  compensation  of  regular  employees  of the
Company, which shall be paid in any event by the Company).

          "Selling  Expenses" shall mean all underwriting  discounts and selling
commissions applicable to the sale of Shares and Warrant Shares and all fees and
disbursements of counsel to Investor.

          "Shares"  means the shares of the Company's  common stock  exercisable
upon exercise of the Warrants.

          "Investor"  means  the  person  set  forth  above  and  any  permitted
assignee.

          (b) Company Registration.

               i) Notice of  Registration.  If, at any time after June 30, 1996,
the Company shall determine to register any of its securities either for its own
account  or the  account  of a  security  holder  or  holders  exercising  their
respective demand registration rights, other than a registration relating solely
to employee  benefit plans,  or a registration  relating  solely to a Commission
Rule 145 transaction,  or a registration on any registration form which does not
permit secondary sales, the Company will:

                    a) promptly give to Investor  written  notice thereof (which
shall  include a list of the  jurisdictions  in which  the  Company  intends  to
attempt to qualify such securities  under the applicable blue sky or other state
securities laws); and

                    b)   include   in  such   registration   (and  any   related
qualification under blue sky laws or other compliance),  and in any underwriting
involved  therein,  all the Shares and  Warrant  Shares  specified  in a written
request or requests,  made by Investor within fifteen (15) days after receipt of
the written notice from the Company  described in this clause (i), except as set
forth in Section 5(b)(ii) below.

               ii) Underwriting.  If the registration of which the Company gives
notice is for a  registered  public  offering  involving  an  underwriting:  the
Company shall so advise Investor as part of the written notice given pursuant to
Section  5(b)  hereof.  In such event,  the right of  Investor  to  registration
pursuant to this Section 5 shall be conditioned upon Investor's participation in
such  underwriting and the inclusion of Investor's  Shares and Warrant Shares in
the  underwriting to the extent provided  herein.  Investor shall (together with
the Company, its directors and officers, and any other shareholders distributing
their securities through such underwriting) enter into an underwriting agreement
in customary form with the underwriter or underwriters selected for underwriting
by the Company.

     Notwithstanding  any other  provision of this Section 5, if the underwriter
determines that

                                       41

<PAGE>

marketing   factors  require  a  limitation  on  the  number  of  shares  to  be
underwritten,   the   underwriter  may  exclude  from  such   registration   and
underwriting  some or all of the Shares and Warrant Shares which would otherwise
be underwritten pursuant hereto. Any securities so excluded shall be apportioned
pro rata among Investor and any other shareholders distributing their securities
through such underwriting  according to the total amount of securities otherwise
entitled  to be included  therein  owned by such  shareholders  or in such other
proportions as shall mutually be agreed upon.

     If Investor disapproves of the terms of any such underwriting, it may elect
to withdraw therefrom by written notice to the Company and the underwriter.  Any
Shares and Warrant Shares excluded or withdrawn from such underwriting  shall be
withdrawn from such registration.

     The Company  shall bear all  Registration  Expenses  incurred in connection
with any  registration,  qualification and compliance by the Company pursuant to
this  Section  5. All  Selling  Expenses  shall be borne by the  holders  of the
securities so registered  pro rata on the basis of the number of their shares so
registered.

               iii)  Registration  Procedures.   In  the  case  of  registration
effected  by the  Company  pursuant to this  Agreement,  the  Company  will keep
Investor  advised in writing as to the initiation of registration  and as to the
completion thereof. At its expense, the Company will:

                    a) keep  such  registration  effective  for a period  of one
hundred  twenty (120) days or until  Investor  has  completed  the  distribution
described  in the  registration  statement  relating  thereto,  whichever  first
occurs;

                    b) furnish such number of  prospectuses  and other documents
incident thereto as Investor from time to time may reasonably request; and

                    c) use its best  efforts to  register  or qualify the Shares
and Warrant Shares under the  securities or blue sky laws of such  jurisdictions
as Investor  may  request;  provided,  however,  that the  Company  shall not be
obligated  to  register  or  qualify  such  Shares  and  Warrant  Shares  in any
particular  jurisdiction  in which the  Company  would be  required to execute a
general  consent to service  of  process in order to effect  such  registration,
qualification,  or compliance,  unless the Company is already subject to service
in such  jurisdiction  and except as may be  required by the  Securities  Act or
applicable rules or regulations thereunder.

               iv) Indemnification.

                    a) The Company, with respect to registration, qualification,
and  compliance  effected  pursuant to this  Agreement,  will indemnify and hold
harmless  Investor,  each  of  its  officers  and  directors,   and  each  party
controlling Investor, and each underwriter,  if any, and each party who controls
any  underwriter,  against all claims,  losses,  damages,  and  liabilities  (or
actions in respect  thereof) arising out of or based on any untrue statement (or
alleged  untrue  statement)  of a material  fact  contained  in any  prospectus,
offering  circular,  or  other  document  (including  any  related  registration
statement,  notification,  or  the  like)  incident  to any  such  registration,
qualification,  or compliance, or based on any omission (or alleged omission) to
state therein a material fact required to be stated therein or necessary to make
the statements  therein not  misleading,  or any violation by the Company of the
Securities  Act or any rule or regulation  thereunder  applicable to the Company
and relating to action or inaction  required of the Company in  

                                       42

<PAGE>

connection with any such registration,  qualification,  or compliance,  and will
reimburse  Investor,  its  officers  and  directors,  and any party  controlling
Investor, such underwriter and party who controls any such underwriter,  for any
legal and any other  expenses  incurred  in  connection  with  investigating  or
defending any such claim, loss, damage,  liability, or action, provided that the
Company  will not be liable in any such case to the extent  that any such claim,
loss,  damage,  liability,  or  expense  arises out of or is based on any untrue
statement or omission  based solely upon  written  information  furnished to the
Company by  Investor or such  underwriter,  as the case may be, and stated to be
specifically for use therein.

                    b) Investor  will,  if Shares and Warrant  Shares held by it
are included in the securities as to which such registration,  qualification, or
compliance is being effected,  indemnify and hold harmless the Company,  each of
its  directors  and  officers,  and each  underwriter,  if any, of the Company's
securities covered by such a registration statement, and each party who controls
the  Company or such  underwriter,  against  all claims,  losses,  damages,  and
liabilities  (or  actions in  respect  thereof)  arising  out of or based on any
untrue  statement (or alleged untrue  statement) of a material fact contained in
any  such  registration  statement,  prospectus,  offering  circular,  or  other
document, or any omission (or alleged omission) to state therein a material fact
required to be stated  therein or necessary to make the  statements  therein not
misleading,  and will reimburse the Company, its officers and directors, and the
underwriters  or control  persons,  if any, for any legal or any other  expenses
reasonably  incurred in  connection  with  investigating  or defending  any such
claim, loss, damage,  liability, or action, in each case to the extent, but only
to the extent,  that such untrue  statement  (or alleged  untrue  statement)  or
omission  (or  alleged  omission)  is  made  in  such  registration   statement,
prospectus,  offering circular, or other document solely in reliance upon and in
conformity  with  written  information  furnished to the Company by Investor and
stated  to  be  specifically  for  use  therein;  provided,  however,  that  the
obligations  of Investor  hereunder  shall be limited to an amount  equal to the
proceeds to Investor of securities sold as contemplated herein.

                    c) Each party entitled to indemnification under this Section
5 (the  "Indemnified  Party") shall give notice to the party required to provide
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the  Indemnifying  Party to assume  the  defense of any such claim or any
litigation  resulting  therefrom,  provided  that  counsel for the  Indemnifying
Party,  who shall conduct the defense of such claim or any litigation  resulting
therefrom,  shall be approved by the Indemnified Party (whose approval shall not
unreasonably  be withheld),  and the  Indemnified  Party may participate in such
defense at such party's expense  (unless the  Indemnified  Party shall have been
advised by counsel  that actual or  potential  differing  interests  or defenses
exist or may exist between the Indemnifying  Party and the Indemnified Party, in
which case such expense shall be paid by the Indemnifying  Party),  and provided
further  that the  failure of any  Indemnified  Party to give notice as provided
herein shall not relieve the  Indemnifying  Party of its obligations  under this
Section  5.  No  Indemnifying  Party,  in the  defense  of  any  such  claim  or
litigation,  shall,  except with the consent of  Indemnified  Party,  consent to
entry of any judgment or enter into any settlement  which does not include as an
unconditional  term  thereof  the giving by the  claimant or  plaintiff  to such
Indemnified  Party of a release  from all  liability in respect to such claim or
litigation.


                                       43

<PAGE>

                    v)  Information  by Investor.  Investor shall furnish to the
Company  such  information  regarding  Investor as the  Company  may  reasonably
request in writing and as shall be reasonably  required in  connection  with any
registration, qualification, or compliance referred to in this Agreement.

                    vi) Transfer of Registration Rights. The rights set forth in
this Agreement may be  transferred in any transfer of the Shares,  provided that
the Company is given written notice of such transfer, and provided further, that
the  rights  set forth in this  Agreement  may only be  transferred  to a single
transferee.

     8.  Governing  Law.  This  Agreement  shall be governed by and construed in
accordance with the laws of the State of California.

     9.  Counterparts.   This  Agreement  may  be  executed  in  any  number  of
counterparts,  each of which  shall be an  original,  but all of which  together
shall constitute one instrument.

     IN WITNESS  WHEREOF,  the  undersigned  purchasers  of  securities  and the
Company have executed this Agreement as of the day and year first above written.

                                    COMPANY:

                                       IMATRON INC.

                                       By:___________________________
                                               President

                                    INVESTOR:


                                       ______________________________
                                                GARY POST


                                       44

<PAGE>



                              IMATRON INC. FORM S-3

                             Schedule to Exhibit 4.4
                    Pursuant to Instruction No. 2 to Item 601
                                of Regulation S-K

         The form of Stock  Purchase  Agreement  filed  as  Exhibit  4.4 to this
Registration  Statement is substantially  identical in all material  respects to
the Stock Purchase  Agreement is issued by the Company to Ambient Capital Group,
Inc. dated March 8, 1996 and to Sitrick and Company Inc. on August 12, 1996. The
Schedule sets forth the material  details of such  agreements  which differ from
the form of exhibit filed herewith.

Name of Warrantholder                       Number of Common Shares Exercisable
- ---------------------                       -----------------------------------

Ambient Capital Group, Inc.                                87,720
Sitrick and Company Inc.                                   55,309




                                       45



                                   Exhibit 4.5





                                       46

<PAGE>

THESE  SECURITIES  HAVE  NOT BEEN  REGISTERED  WITH THE  SECURITIES AND EXCHANGE
COMMISSION UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND ANY SALE, TRANSFER,
PLEDGE OR OTHER DISPOSITION THEREOF MAY BE MADE ONLY (i) IN A REGISTRATION UNDER
SAID ACT OR (ii) IF AN EXEMPTION FROM  REGISTRATION  UNDER SAID ACT IS AVAILABLE
AND THE  COMPANY HAS  RECEIVED  AN OPINION OF COUNSEL TO THAT EFFECT  REASONABLY
SATISFACTORY TO IT.


                                  IMATRON INC.

                          COMMON STOCK PURCHASE WARRANT

                     This Warrant Expires December 31, 2000


Warrant No. 96-4                                                Shares: 219,300

         THIS CERTIFIES  that,  subject to the terms and  conditions  herein set
forth, GARY POST (the "Holder") is entitled to purchase from Imatron Inc., a New
Jersey corporation (the "Company"),  at any time or from time to time during the
Exercise  Period  (as  hereinafter   defined)  the  number  of  fully  paid  and
non-assessable  shares of Common Stock of the Company (the "Shares") as provided
herein upon surrender hereof at the principal office of the Company, and, at the
election of the holder hereof, upon payment of the purchase price at said office
in cash or by  cashier's  check  or by the  wire  transfer  of funds in a dollar
amount equal to the purchase price of the Shares for which the  consideration is
being  given.  This  Warrant  is  issued  under and in  accordance  with a Stock
Purchase  Agreement (the "Stock Purchase  Agreement")  dated as of March 8, 1996
between the Company and the Holder,  and is subject to the terms and  provisions
contained in the Stock Purchase Agreement.

         This  Warrant  shall be  exercisable  for that number of  Shares as set
forth  above,  in minimum  units of 10,000 shares.

         1. Purchase Price. Subject to adjustment as hereinafter  provided,  the
purchase  price of one  share of  Common  Stock  (or such  securities  as may be
substituted for one share of Common Stock pursuant to the provisions hereinafter
set forth)  (the  "Warrant  Price")  shall be One Dollar and  Seventy-One  Cents
($1.71).

         2. Adjustment of Warrant Price and Number of Shares. In addition to the
adjustment  provided for in Section 1 above,  the number and kind of  securities
issuable upon the exercise of this Warrant  shall be subject to adjustment  from
time to time upon the happening of certain events as follows:

                  a.  Adjustment for Dividends in Stock.  In case at any time or
from time to time on or after the date hereof the holders of the Common Stock of
the Company (or any shares of stock or other  securities at the time  receivable
upon the  exercise of this  Warrant)  shall have  received,  or, on or after the
record date fixed for the  determination  of eligible  stockholders,  shall have
become entitled to receive,  without payment therefor, other or additional stock
of the Company by way of dividend  (other than as provided for in Paragraph 2(b)
below),  then and in each such case, the holder of this Warrant shall,  upon the
exercise hereof, be entitled to receive,  in addition to the number of shares of
Common  Stock  receivable  thereupon,  and  without  payment  of any  additional
consideration  therefor,  the  amount of such other or  additional  stock of the
Company  which such holder  would hold on the date of such  exercise had it been
the holder of record of such Common Stock on the date hereof and had thereafter,
during  the  period  from  the date  hereof  to and  including  the date of such
exercise,  retained such shares and/or all other  additional stock receivable by
it as aforesaid during such period,  given effect to all adjustments  called for
during such period by this Paragraph 2.

                  b.  Adjustment  for Changes in Common  Stock.  In the event of
changes in the  outstanding  Common Stock of the Company by reason of split-ups,
recapitalizations,  reclassifications,  mergers, consolidations, combinations or
exchanges of shares, separations,  reorganizations,  liquidations,  or the like,
the number and class of shares  available under the Warrant in the aggregate and
the Warrant Price shall be correspondingly adjusted by the Board of Directors of
the Company. The adjustment shall be such as will give the holder of the Warrant
on exercise for 

                                       47

<PAGE>

the same aggregate Warrant Price the total number,  class, and kind of shares as
he would have owned had the Warrant been exercised prior to the event and had he
continued to hold such shares until after the event requiring adjustment.

         3. No Fractional  Shares.  No fractional shares of Common Stock will be
issued in connection with any subscription  hereunder. In lieu of any fractional
shares which would  otherwise be issuable,  the Company  shall pay cash equal to
the product of such fraction multiplied by the fair market value of one share of
Common Stock on the date of exercise,  as determined by the fair market value of
one share of the Company's Common Stock on the date of exercise as determined in
good faith by the Company's Board of Directors.

         4.  No  Stockholder  Rights. This Warrant  shall not entitle its holder
to any of the rights of a stockholder of the Company prior to exercise thereof.

         5. Reservation of Stock.  The Company  covenants that during the period
this Warrant is  exercisable,  the Company will reserve from its  authorized and
unissued Common Stock a sufficient  number of shares to provide for the issuance
of Common Stock upon the exercise of this Warrant.  The Company  agrees that its
issuance of this Warrant shall constitute full authority to its officers who are
charged with the duty of executing  stock  certificates to execute and issue the
necessary  certificates  for shares of Common  Stock upon the  exercise  of this
Warrant.

         6. Exercise of Warrant. This Warrant may be exercised by the registered
holder or its  registered  assigns,  in whole or in part and in minimum units of
10,000 shares,  by the surrender of this Warrant at the principal  office of the
Company,   together  with  the  form  of  subscription   hereof  duly  executed,
accompanied  by payment in full of the amount of the  Warrant  Price in the form
described  in this  Warrant.  Upon  partial  exercise  hereof,  a new warrant or
warrants containing the same date and provisions as this Warrant shall be issued
by the Company to the registered holder for the number of shares of Common Stock
with  respect to which this  Warrant  shall not have been  exercised.  A Warrant
shall be  deemed  to have  been  exercised  immediately  prior  to the  close of
business on the date of its  surrender for exercise as provided  above,  and the
person  entitled  to  receive  the  shares of Common  Stock  issuable  upon such
exercise  shall be treated  for all  purposes  as the  holder of such  shares of
record as of the close of business on such date. As promptly as  practicable  on
or after such date, the Company shall issue and deliver to the person or persons
entitled to receive the same, a certificate  or  certificates  for the number of
full shares of Common Stock issuable upon such  exercise,  together with cash in
lieu of any fraction of a share as provided above.

         7. Certificate of Adjustment. Whenever the Warrant Price is adjusted as
herein provided, the Company shall promptly deliver to the record holder of this
Warrant a  certificate  of an officer of the Company  setting forth the relevant
Warrant  Price or number of shares  after such  adjustment  and setting  forth a
brief statement of the facts requiring such adjustment.

         8.  Compliance  With  Securities  Act. The holder of this  Warrant,  by
acceptance hereof, agrees that this Warrant and the shares of Common Stock to be
issued upon  exercise  hereof (or shares of any security  into which such Common
Stock may be converted)  are being  acquired for  investment and that the holder
will not offer,  sell,  or  otherwise  dispose of this Warrant and any shares of
Common Stock to be issued upon  exercise  hereof (or shares of any security into
which such Common Stock may be converted) except under  circumstances which will
not result in a violation of the Securities Act of 1933, as amended (the "Act").
Upon  exercise of this Warrant,  the holder  hereof  shall,  if requested by the
Company,  confirm  in writing  its  investment  purpose  and  acceptance  of the
restrictions on transfer of the shares of Common Stock.

         9. Subdivision of Warrant. At the request of the holder of this Warrant
in  connection  with a transfer or exercise  of a portion of the  Warrant,  upon
surrender of such  Warrant for such  purpose to the Company,  the Company at its
expense  (except for any transfer tax payable) will issue and exchange  therefor
warrants  of like  tenor and date  representing  in the  aggregate  the right to
purchase  such number of shares of such Common Stock as shall be  designated  by
such holder at the time of such surrender; provided, however, that the Company's
obligations to subdivide  securities  under this section shall be subject to and
conditioned  upon the compliance of any such  subdivision  with applicable state
securities laws and with the Act.

         10. Loss, Theft, Destruction, or Mutilation of Warrant. Upon receipt by
the  Company  of  evidence  reasonably  satisfactory  to it of the loss,  theft,
destruction,  or  mutilation  of this Warrant,  and in case of loss,  theft,  or
destruction,  of indemnity or security  reasonably  satisfactory to it, and upon
reimbursement to the Company of all 

                                       48

<PAGE>

reasonable expenses  incidental thereto,  and upon surrender and cancellation of
this Warrant,  if mutilated,  the Company will make and deliver a new Warrant of
like tenor and dates as of such cancellation, in lieu of this Warrant.

         11.  Miscellaneous.  This Warrant  shall be governed by the laws of the
State  of  California.  The  headings  in  this  Warrant  are  for  purposes  of
convenience  and  reference  only,  and shall not be deemed to constitute a part
hereof.  Neither  this  Warrant  nor any term  hereof  may be  changed,  waived,
discharged,  or terminated orally but only by an instrument in writing signed by
the  Company  and  the  registered   holder   hereof.   All  notices  and  other
communications  from the  Company  to the  holder  of this  Warrant  shall be by
telecopy or expedited courier service to the address furnished to the Company in
writing by the last holder of this  Warrant who shall have  furnished an address
to the Company in writing.

         12.  Exercise  Period.  The  Exercise  Period  shall  mean  the  period
commencing on the date hereof and ending on December 31, 2000.


         ISSUED this 20th day of February, 1996.

                                             IMATRON INC.


                                             By________________________________
                                                S. Lewis Meyer, President
ATTEST:


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



                                       49

<PAGE>

                               FORM OF ASSIGNMENT

                                  IMATRON INC.

         FOR VALUE  RECEIVED the  undersigned  registered  owner of this Warrant
hereby sells,  assigns,  and transfers  unto the Assignee named below all of the
rights of the undersigned  under the within Warrant,  with respect to the number
of shares of Common Stock set forth below.

Name of Assignee              Address                 Number of Shares
- ----------------              -------                 ----------------



and does hereby irrevocably constitute and appoint _____________________________
Attorney to make such transfer on the books of IMATRON INC.  maintained  for the
purpose, with full power of substitution in the premises.

Dated:______________________

                                             ___________________________________
                                             Name of Warrant Holder

                                             Signature:  ______________________


Witness:   ______________________


                                       50

<PAGE>

                                SUBSCRIPTION FORM
                                  IMATRON INC.

                 (To be executed only upon exercise of Warrant)

         The undersigned  registered owner of this Warrant irrevocably exercises
this  Warrant  for and  purchases  ________________  of the  number of shares of
Common Stock of IMATRON INC.  purchasable with this Warrant,  and herewith makes
payment therefor,  all at the price and on the terms and conditions specified in
this Warrant.

Dated:_____________________
                                               --------------------------------
                                               (Signature of Registered Owner)

                                               --------------------------------
                                                     (Street Address)

                                               --------------------------------
                                               (City)    (State)    (Zip Code)



                                       51

<PAGE>

                              IMATRON INC. FORM S-3

                             Schedule to Exhibit 4.5
                    Pursuant to Instruction No. 2 to Item 601
                                of Regulation S-K

         The form of Common Stock Purchase  Warrant filed as Exhibit 4.5 to this
Registration  Statement is substantially  identical in all material  respects to
the Common Stock  Purchase  Warrant is issued by the Company to Ambient  Capital
Group,  Inc.  dated March 8, 1996 and to Sitrick and Company  Inc. on August 12,
1996. The Schedule sets forth the material details of such Warrants which differ
from the exhibit filed herewith.

Name of Warrantholder                       Number of Common Shares Exercisable
- ---------------------                       -----------------------------------

Ambient Capital Group, Inc.                               87,720
Sitrick and Company Inc.                                  55,309





                                       52



                                   Exhibit 5.1




                                       53

<PAGE>



                                SEVERSON & WERSON
                           A PROFESSIONAL CORPORATION
                                ATTORNEYS AT LAW
                             ONE EMBARCADERO CENTER
                         SAN FRANCISCO, CALIFORNIA 94111

                               FAX (415) 956-0439
                            TELEPHONE (415) 398-3344


                                September 4, 1996



Imatron Inc.
389 Oyster Point Boulevard
South San Francisco, California 94080

Gentlemen:

         You have  requested  our  opinion  with  respect to certain  matters in
connection  with the filing by Imatron Inc. (the  "Company")  of a  Registration
Statement on Form S-3 (the  "Registration  Statement")  with the  Securities and
Exchange  Commission  on behalf of certain  Selling  Shareholders  covering  the
offering of up to 3,810,155 shares of the Company's Common Stock (the "Shares").
Such total includes  69,542 shares  currently  issued and  outstanding;  540,613
shares  which are  issuable  upon the  exercise  of  outstanding  warrants;  and
3,200,000  shares which are issuable  upon the  exercise of  outstanding  Common
Stock  exchange  rights.  All of the  outstanding  shares,  the warrants and the
exchange  rights  were   previously   issued  by  the  Company  to  the  Selling
Shareholders in private transactions.

         In connection  with this opinion,  we have examined and relied upon the
Registration  Statement and related  Prospectus,  the Company's  Certificate  of
Incorporation  and  Bylaws,  as  amended,  and such  other  records,  documents,
certificates,  memoranda and other  instruments as in our judgment are necessary
or  appropriate  to enable us to render the  opinion  expressed  below.  We have
assumed the  genuineness and  authenticity  of all documents  submitted to us as
originals,  the  conformity  to  originals of all  documents  submitted to us as
copies  thereof,  and the due execution  and delivery of all documents  were due
execution and delivery are a prerequisite to the effectiveness thereof.

         We do not hold ourselves out as experts in the laws of the State of New
Jersey and our  opinion is based  solely on a review of the New Jersey  Business
Corporation Act, as reported in unofficial compilations.

         On the basis of the foregoing,  and in reliance thereon,  we are of the
opinion that:

         The Shares,  when sold and issued in accordance  with the  Registration
Statement  and related  Prospectus,  will be validly  issued,  fully  paid,  and
nonassessable.

                                       54

<PAGE>

         This opinion is intended  solely for your benefit and is not to be made
available to or be relied upon by any other person,  firm or entity  without our
prior written consent.

         We  consent  to  the  filing  of  this  opinion  as an  exhibit  to the
Registration Statement.


                                             SEVERSON & WERSON
                                             A Professional Corporation


                                             By: /s/ Roger S. Mertz
                                                --------------------------------
                                                     Roger S. Mertz
RSM/kw


                                       55




                                  Exhibit 24.1





                                       56

<PAGE>


               Consent of Ernst & Young LLP, Independent Auditors

         We consent to the reference to our firm under the caption  "Experts" in
the Registration Statement (Form S-3) and related Prospectus of Imatron Inc. for
the   registration  of  3,810,155   shares  of  its  Common  Stock  and  to  the
incorporation  by reference  therein of our report  dated  February 9, 1996 with
respect to the consolidated financial statements of Imatron Inc. included in its
Annual Report (Form 10-K) for the year ended  December 31, 1995,  filed with the
Securities and Exchange Commission.


                                                         /s/ ERNST & YOUNG, LLP
                                                         -----------------------
                                                         Ernst & Young, LLP

September 5, 1996



                                       57



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