PERCLOSE INC
S-3, 1997-11-06
SURGICAL & MEDICAL INSTRUMENTS & APPARATUS
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<PAGE>
    AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON NOVEMBER 5, 1997
                                                    REGISTRATION NO. 333-
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                 --------------
 
                                    FORM S-3
            REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933
                                 --------------
 
                                 PERCLOSE, INC.
 
             (Exact name of Registrant as specified in its charter)
 
<TABLE>
<S>                              <C>
           DELAWARE                 94-3154669
   (State of incorporation)      (I.R.S. Employer
                                  Identification
                                     Number)
</TABLE>
 
  (Address, including zip code, and telephone number, including area code, of
                   Registrant's principal executive offices)
 
                              HENRY A. PLAIN, JR.
                     PRESIDENT AND CHIEF EXECUTIVE OFFICER
                                 PERCLOSE, INC.
                              199 JEFFERSON DRIVE
                          MENLO PARK, CALIFORNIA 94025
                                 (650) 473-3100
 
 (Name, address, including zip code, and telephone number, including area code,
                             of agent for service)
                                ----------------
 
                                   COPIES TO:
 
        J. CASEY MCGLYNN, ESQ.                    MICHAEL W. HALL, ESQ.
    CHRISTOPHER D. MITCHELL, ESQ.                ROBERT V. W. ZIPP, ESQ.
        ROGER E. GEORGE, ESQ.                    TAMARA L. THOMPSON, ESQ.
   Wilson Sonsini Goodrich & Rosati                 Venture Law Group
       Professional Corporation                 A Professional Corporation
          650 Page Mill Road                       2800 Sand Hill Road
     Palo Alto, California 94304               Menlo Park, California 94025
            (650)493-9300                             (650)854-4488
 
                                ----------------
 
    APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: As soon as
practicable after the effective date of this Registration Statement and the
Underwriting Agreement is executed.
                                ----------------
 
    If only the 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 in connection with dividend or interest
reinvestment plans, check the following box. / /
 
    If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. / /
 
    If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. / /
 
    If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. / /
 
                        CALCULATION OF REGISTRATION FEE
 
<TABLE>
<CAPTION>
                                                                   PROPOSED MAXIMUM
                                                  NUMBER OF           AGGREGATE        PROPOSED MAXIMUM
           TITLE OF EACH CLASS OF                SHARES TO BE     OFFERING PRICE PER      AGGREGATE           AMOUNT OF
        SECURITIES TO BE REGISTERED               REGISTERED            SHARE         OFFERING PRICE(1)    REGISTRATION FEE
<S>                                           <C>                 <C>                 <C>                 <C>
Common Stock, $.001 par value...............      1,150,000             $23.50           $27,025,000            $8,189
</TABLE>
 
(1) Estimated solely for the purpose of computing the amount of the registration
    fee. The estimate is made pursuant to Rule 457(c) of the Securities Act of
    1933, as amended.
 
    THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF
THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SUCH SECTION 8(A),
MAY DETERMINE.
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<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.
<PAGE>
                                                           SUBJECT TO COMPLETION
                                                                NOVEMBER 5, 1997
 
                                1,000,000 SHARES
 
                                     [LOGO]
 
                                  COMMON STOCK
                                   ---------
 
    All of the shares of common stock, $.001 par value per share (the "Common
Stock") offered hereby are being sold by Perclose, Inc. ("Perclose" or the
"Company"). The Company's Common Stock is traded on the Nasdaq Stock Market's
National Market (the "Nasdaq National Market") under the symbol "PERC." On
November 5, 1997, the last reported sale price for the Company's Common Stock
was $25.75 per share. See "Price Range of Common Stock and Dividend Policy."
 
                                 --------------
 
        THE COMMON STOCK OFFERED HEREBY INVOLVED A HIGH DEGREE OF RISK.
                 SEE "RISK FACTORS" APPEARING ON PAGES 6 TO 13.
                                 -------------
 
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
  EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE
    SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION
      PASSED UPON THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY
       REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
<TABLE>
<CAPTION>
                                                       UNDERWRITING
                                                      DISCOUNTS AND          PROCEEDS TO
                               PRICE TO PUBLIC         COMMISSIONS            COMPANY(1)
<S>                          <C>                   <C>                   <C>
Per Share..................           $                     $                     $
Total(2)...................           $                     $                     $
</TABLE>
 
(1) Before deducting expenses of the offering estimated at $350,000 payable by
    the Company.
 
(2) The Company has granted the Underwriters a 30-day option to purchase up to
    150,000 additional shares of Common Stock solely to cover over-allotments,
    if any. To the extent that the option is exercised, the Underwriters will
    offer the additional shares at the Price to Public shown above. If the
    option is exercised in full, the total Price to Public, Underwriting
    Discounts and Commissions and Proceeds to Company will be $      , $      ,
    and $      , respectively. See "Underwriting."
 
                                 --------------
 
    The shares of Common Stock are offered by the several Underwriters, subject
to prior sale, when, as and if delivered to and accepted by them, and subject to
the right of the Underwriters to reject any order in whole or in part. It is
expected that delivery of the shares of Common Stock will be made at the offices
of BT Alex. Brown Incorporated, Baltimore, Maryland on or about           ,
1997.
 
                                 --------------
 
BT ALEX. BROWN                                                PIPER JAFFRAY INC.
 
               THE DATE OF THIS PROSPECTUS IS             , 1997
<PAGE>
    CERTAIN PERSONS PARTICIPATING IN THIS OFFERING MAY ENGAGE IN TRANSACTIONS
THAT STABILIZE, MAINTAIN, OR OTHERWISE AFFECT THE PRICE OF THE COMMON STOCK.
SUCH TRANSACTIONS MAY INCLUDE THE PURCHASE OF SHARES OF COMMON STOCK FOLLOWING
THE OFFERING TO COVER A SYNDICATE SHORT POSITION IN THE COMMON STOCK OR MAINTAIN
THE PRICE OF THE COMMON STOCK, AND THE IMPOSITION OF PENALTY BIDS. FOR A
DESCRIPTION OF THESE ACTIVITIES, SEE "UNDERWRITING."
 
    IN CONNECTION WITH THIS OFFERING, CERTAIN UNDERWRITERS AND OTHER SELLING
GROUP MEMBERS OR THEIR AFFILIATES MAY ENGAGE IN PASSIVE MARKET MAKING
TRANSACTIONS IN THE COMMON STOCK ON THE NASDAQ NATIONAL MARKET IN ACCORDANCE
WITH RULE 103 OF REGULATION M. SEE "UNDERWRITING."
 
                INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE
 
    The following documents which have been filed with the Commission pursuant
to the Securities and Exchange Act of 1934, as amended (the "Exchange Act") are
hereby incorporated by reference:
 
    (1) The Company's Annual Report on Form 10-K for the fiscal year ended March
       31, 1997.
 
    (2) The description of the Company's capital stock, including Preferred
       Share Purchase Rights, which is contained in the Registration Statement
       on Form 8-A filed pursuant to Section 12 of the Exchange Act on January
       28, 1997.
 
    (3) The Company's Proxy Statement for its 1997 annual meeting of
       stockholders filed pursuant to Section 14 of the Exchange Act on June 12,
       1997.
 
    (4) The Company's Quarterly Report on Form 10-Q for the fiscal quarter ended
       June 30, 1997 filed pursuant to Section 13 of the Exchange Act on August
       14, 1997.
 
    All documents filed by the Company pursuant to Sections 13(a), 13(c), 14 or
15(d) of the Exchange Act after the date of this Registration Statement of which
this Prospectus forms a part and prior to the termination of the offering of the
Securities offered hereby shall be deemed to be incorporated by reference into
this Prospectus and be a part hereof from the date of filing such documents.
 
    Any statement contained in a document incorporated or deemed to be
incorporated by reference herein shall be deemed to be modified or superseded
for purposes of the Registration Statement or this Prospectus to the extent that
a statement contained herein, in a Prospectus Supplement or in any other
document subsequently filed with the Commission which also is or is deemed to be
incorporated by reference herein modifies or supersedes such statement. Any such
statement so modified or superseded shall not be deemed, except as so modified
or superseded, to constitute a part of the Registration Statement or this
Prospectus.
 
    The Company will furnish without charge to each person, including any
beneficial owner, to whom this Prospectus is delivered, on the written or oral
request of such person made to the Company's offices, a copy of any or all of
the documents incorporated by reference, other than exhibits to such documents
(unless such exhibits are specifically incorporated by reference into such
documents).
 
                                       2
<PAGE>
                               PROSPECTUS SUMMARY
 
    THE FOLLOWING SUMMARY IS QUALIFIED IN ITS ENTIRETY BY THE MORE DETAILED
INFORMATION AND THE FINANCIAL STATEMENTS AND NOTES THERETO INCORPORATED BY
REFERENCE HEREIN. EXCEPT AS OTHERWISE INDICATED, ALL INFORMATION IN THIS
PROSPECTUS ASSUMES NO EXERCISE OF THE UNDERWRITERS' OVER-ALLOTMENT OPTION. SEE
"UNDERWRITING."
 
                                  THE COMPANY
 
    Perclose designs, develops, manufactures and markets minimally invasive
medical devices that automate the delivery of needles and sutures for the
surgical closure of arterial access sites in coronary catheterization
procedures. The Company is also developing devices for the connection of blood
vessels in conventional and minimally invasive coronary artery bypass graft
("CABG") procedures. The Company's first products, the Prostar and Techstar
products, are a family of devices that surgically close arterial access sites
after catheterization procedures such as angioplasty, stenting, atherectomy and
angiography, termed percutaneous vascular surgery ("PVS"). The Prostar and
Techstar PVS products are designed to provide routine, definitive closure that
replicates results previously obtainable only through open surgery, without the
associated risks and costs. Randomized clinical trials of the Prostar and
Techstar products have demonstrated significant clinical and economic advantages
over conventional compression methods of arterial access site closure. These
advantages include achieving rapid hemostasis (the cessation of bleeding),
reducing nursing time required to monitor patients, allowing earlier patient
ambulation and discharge, enabling more efficient use of the catheterization
laboratory, reducing overall treatment costs and improving patient comfort. In
addition, for certain high risk patients, such as those who have experienced a
heart attack, the Company's products allow continuation of aggressive
anticoagulation, thrombolytic or anti-restenosis drug therapy without increasing
the risk of bleeding complications at the arterial access site.
 
    The Company commenced international shipments of its first Prostar and
Techstar products in December 1994 and July 1995, respectively. In April 1997,
the Company received FDA Premarket Approval ("PMA") for commercial sale in the
United States of the initial Prostar products. In November 1997, the Company
received PMA supplement approval for commercial sale in the United States of its
initial Techstar and Techstar XL products. In June 1997, the Company submitted
to the FDA a PMA supplement seeking approval for commercial sale in the United
States of certain Prostar Plus and Prostar XL products.
 
    Industry estimates in 1997 indicate that therapeutic and diagnostic coronary
catheterizations represent approximately 3.5 million procedures annually
worldwide, including approximately 2.1 million in the United States. Of the 3.5
million total procedures, approximately 675,000 are therapeutic procedures, of
which approximately 425,000 occur in the United States. Of the remaining
approximately 2.9 million diagnostic procedures, approximately 1.7 million occur
in the United States.
 
    The Company is also developing the Heartflo anastomosis system to allow
cardiac surgeons to automate the rapid placement of sutures in blood vessels
during CABG surgery. The success of a CABG procedure is largely determined by
the quality of the anastomosis (attachment), which dictates the long-term
patency, or blood flow, through the vein graft to the coronary arteries. While
cardiac surgeons have developed effective surgical techniques to perform
hand-sewn anastomoses of coronary blood vessels in conventional CABG surgeries,
the recent emergence of minimally invasive CABG procedures introduces additional
challenges for performing hand-sewn anastomoses during such procedures. Since
the opening to the chest cavity created by ports or mini-thoracotomies used in
minimally invasive CABG procedures is small, accessing and suturing the bypass
graft to the coronary artery is more difficult, may take longer to perform and
may not achieve the same therapeutic results as in conventional open chest CABG
surgery. The Heartflo system is being designed to replicate an ideal suture
pattern in a rapid and automated fashion while still allowing the surgeon
ultimate control over the tensioning and tying of the sutures to complete
attachment of the bypass graft. The Heartflo system is being designed for use
with conventional, open chest CABG procedures and the newer, minimally invasive,
beating heart and
 
                                       3
<PAGE>
stopped heart procedures. The Heartflo system is currently undergoing
preclinical testing. Industry estimates in 1997 indicate that there are
approximately 540,000 CABG procedures performed annually worldwide, with 320,000
of those occurring in the United States.
 
    The Company's objectives are to become the leader in the design, development
and commercialization of suture-based closure devices, to establish percutaneous
vascular surgery using the Company's products as the standard of care for
post-catheterization arterial access site management and to commercialize new
devices based on the Company's core technology that improve clinical outcomes
and reduce costs. Key elements of the Company's strategy include demonstrating
the clinical and cost advantages of its products over conventional closure
methods, extending the Company's technology platform and expanding the markets
for its existing products. The Company also plans to develop additional versions
of its products for new and emerging catheterization procedures, including
procedures involving large diameter catheter devices where arterial access site
closure can be particularly difficult.
 
                                       4
<PAGE>
                                  THE OFFERING
 
<TABLE>
<S>                                 <C>
Common Stock offered hereby.......  1,000,000 shares
 
Common Stock to be outstanding
  after the offering..............  10,627,497 shares(1)
 
Use of proceeds...................  For funding of product development, capital
                                    expenditures, working capital, leasehold improvements
                                    and general corporate purposes
 
Nasdaq National Market symbol.....  PERC
</TABLE>
 
                         SUMMARY FINANCIAL INFORMATION
 
<TABLE>
<CAPTION>
                                                                                              SIX MONTHS ENDED
                                                               YEARS ENDED MARCH 31,           SEPTEMBER 30,
                                                          --------------------------------  --------------------
                                                            1995       1996        1997       1996       1997
                                                          ---------  ---------  ----------  ---------  ---------
                                                                 (IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)
<S>                                                       <C>        <C>        <C>         <C>        <C>
STATEMENTS OF OPERATIONS DATA:
  Net revenues..........................................  $     178  $   2,457  $    4,456  $   2,535  $   2,380
  Costs and expenses:
    Cost of goods sold, including manufacturing start-up
      costs.............................................      2,149      4,772       4,703      2,223      3,249
    Research and development............................      3,066      3,059       4,745      2,395      2,525
    Marketing, general and administrative...............      2,155      3,486       6,301      2,496      5,581
                                                          ---------  ---------  ----------  ---------  ---------
  Loss from operations..................................     (7,192)    (8,860)    (11,293)    (4,579)    (8,975)
  Interest and other income, net........................        199        776       1,636        890        613
                                                          ---------  ---------  ----------  ---------  ---------
    Net loss............................................  $  (6,993) $  (8,084) $   (9,657) $  (3,689) $  (8,362)
                                                          ---------  ---------  ----------  ---------  ---------
                                                          ---------  ---------  ----------  ---------  ---------
  Net loss per share....................................             $   (1.34) $    (1.01) $   (0.39) $   (0.87)
  Shares used in computing net loss per share...........                 6,025       9,517      9,498      9,598
  Pro forma net loss per share..........................  $   (1.04)
  Shares used in computing pro forma net loss
    per share...........................................      6,717
</TABLE>
 
<TABLE>
<CAPTION>
                                                                                           SEPTEMBER 30, 1997
                                                                                       --------------------------
                                                                                         ACTUAL    AS ADJUSTED(2)
                                                                                       ----------  --------------
                                                                                             (IN THOUSANDS)
<S>                                                                                    <C>         <C>
BALANCE SHEET DATA:
  Cash, cash equivalents and short-term investments..................................  $   17,983    $   41,838
  Total assets.......................................................................      24,643        48,498
  Long-term debt and capital lease obligations, less current portion.................      --            --
  Accumulated deficit................................................................     (36,328)      (36,328)
  Total stockholders' equity.........................................................      21,746        45,601
</TABLE>
 
- ---------
 
(1) Excludes 1,390,773 shares of Common Stock subject to outstanding options
    granted pursuant to the Company's stock option plans as of September 30,
    1997 at a weighted average exercise price of $15.44 per share.
 
(2) Adjusted to give effect to the estimated net proceeds of this offering based
    upon the assumed public offering price of $25.75 per share, and after
    deducting underwriting discounts and commissions and estimated offering
    expenses. See "Use of Proceeds."
 
                                       5
<PAGE>
                                  RISK FACTORS
 
    IN ADDITION TO THE OTHER INFORMATION IN THIS PROSPECTUS, THE FOLLOWING
FACTORS SHOULD BE CONSIDERED CAREFULLY IN EVALUATING AN INVESTMENT IN THE SHARES
OF COMMON STOCK OFFERED BY THIS PROSPECTUS. STATEMENTS INCLUDED IN THIS
PROSPECTUS THAT ARE NOT HISTORICAL OR CURRENT FACTS ARE "FORWARD-LOOKING
STATEMENTS" MADE PURSUANT TO THE SAFE HARBOR PROVISIONS OF THE PRIVATE
SECURITIES LITIGATION REFORM ACT OF 1995 AND ARE SUBJECT TO CERTAIN RISKS AND
UNCERTAINTIES THAT COULD CAUSE ACTUAL RESULTS TO DIFFER MATERIALLY. WHEN USED IN
THIS PROSPECTUS, THE WORDS "EXPECTS," "ANTICIPATES," "ESTIMATES," AND SIMILAR
EXPRESSIONS ARE INTENDED TO IDENTIFY FORWARD-LOOKING STATEMENTS. SUCH STATEMENTS
ARE SUBJECT TO RISKS AND UNCERTAINTIES THAT COULD CAUSE ACTUAL RESULTS TO DIFFER
MATERIALLY FROM THOSE PROJECTED. THESE RISKS AND UNCERTAINTIES INCLUDE, BUT ARE
NOT LIMITED TO, THOSE RISKS DISCUSSED BELOW AND, IN PARTICULAR, THE STATEMENTS
RELATING TO THE COMPANY'S DEPENDENCE ON THE PROSTAR AND TECHSTAR PRODUCTS,
UNCERTAINTY OF MARKET ACCEPTANCE, HISTORY OF LOSSES AND EXPECTATION OF FUTURE
LOSSES, FLUCTUATIONS IN OPERATING RESULTS, GOVERNMENT REGULATION, COMPETITION,
LIMITED MANUFACTURING EXPERIENCE, UNCERTAINTY RELATING TO NEW PRODUCT
DEVELOPMENT, LIMITED SALES AND MARKETING EXPERIENCE, RELIANCE ON PATENTS AND
PROPRIETARY TECHNOLOGY AND UNCERTAINTY RELATING TO THIRD-PARTY REIMBURSEMENT.
 
    DEPENDENCE UPON PROSTAR AND TECHSTAR PRODUCTS.  The Prostar and Techstar
products for percutaneous closure of arterial access sites following
catheterization procedures are currently the Company's only product families.
The Prostar 9F and 11F products and Techstar 6F and Techstar XL 6F products have
received FDA PMA approval for commerical sale in the United States. The Prostar
and Techstar products have also been approved for sale in certain international
markets by the appropriate regulatory authorities. The Company has submitted PMA
supplements to the FDA for the Prostar Plus 8F and 10F and Prostar XL 8F
products; however, such products have not yet been approved as safe and
effective under applicable FDA regulatory guidelines. There can be no assurance
that these products will prove to be safe and effective under applicable
regulatory guidelines. In addition, clinical trial data may identify significant
technical or other obstacles to be overcome prior to obtaining necessary U.S.
regulatory approvals for the Prostar Plus and Prostar XL products or U.S. and
international reimbursement approvals. If the Company is unable to commercialize
the Prostar and Techstar products successfully in the United States, the
Company's business, financial condition and results of operations will be
materially and adversely affected. In addition, there can be no assurance as to
when or whether the Company will receive FDA clearance or approval for sale of
other PVS products or any other products in the United States. There can be no
assurance that the Company's development efforts will be successful or that any
further PVS products or any other product developed by the Company will be safe
or effective, capable of being manufactured in commercial quantities at
acceptable costs, approved by appropriate regulatory and reimbursement
authorities or successfully marketed. Furthermore, because the Prostar and
Techstar products represent the Company's sole near-term product focus, the
Company could be materially and adversely affected if these products are not
successfully commercialized and if future generation products are not
successfully developed, do not receive regulatory approvals and are not
successfully commercialized. See "Business -- Products and Technology."
 
    UNCERTAINTY OF MARKET ACCEPTANCE.  The Company's Prostar and Techstar
products represent a new method of closing arterial access sites and there can
be no assurance that these products will gain any significant degree of market
acceptance among physicians, patients and health care payors, even if necessary
international and U.S. regulatory and reimbursement approvals are obtained. The
Company believes that recommendations and endorsements by physicians will be
essential for market acceptance of the Prostar and Techstar products, and there
can be no assurance that any such recommendations or endorsements will be
obtained. Physicians will not use the Prostar and Techstar products unless they
determine, based on clinical data and other factors, that these products are an
attractive alternative to other means of closing arterial access sites and that
the clinical benefits to the patient and cost savings achieved through use of
these products outweigh the cost of the products. Such determinations will
depend, in part, on the ability of the Company's products to reduce the time to
ambulation and the length of hospital stays associated with coronary
catheterization procedures. Acceptance among physicians will also depend upon
the Company's ability to train interventional cardiologists and other
 
                                       6
<PAGE>
potential users of the Company's products in percutaneous vascular surgery
closure techniques, which such physicians typically have not performed, and the
willingness of such users to learn these new techniques. Failure of the
Company's products to achieve significant market acceptance will have a material
adverse effect on the Company's business, financial condition and results of
operations. See "Business -- Clinical and Regulatory Status," " -- Marketing and
Distribution" and " -- Third-Party Reimbursement."
 
    HISTORY OF LOSSES AND EXPECTATION OF FUTURE LOSSES.  The Company has a
limited history of operations. Since its inception in March 1992, the Company
has been primarily engaged in research and development of its percutaneous
arterial access site closure products. The Company has generated limited
revenues from international sales in certain markets, which sales commenced in
December 1994. Since May 1997, the Company has generated limited revenues from
domestic sales. The Company has experienced significant operating losses since
inception and, as of September 30, 1997, had an accumulated deficit of $36.3
million. The development and commercialization of the Company's current products
and other new products, if any, will require substantial research and
development, clinical, regulatory, manufacturing and other expenditures. The
Company's net loss for the six months ended September 30, 1997 increased to $8.4
million from $3.7 million in the six months ended September 30, 1996 primarily
as a result of increased sales and marketing expenses associated with hiring
sales personnel in preparation for introduction of the Prostar 9F and 11F
products and the Techstar 6F and Techstar XL 6F products. The Company expects
its operating losses to continue for at least the next three fiscal quarters as
it continues to expend substantial resources in funding clinical trials in
support of regulatory and reimbursement approvals, expansion of manufacturing,
marketing and sales activities and research and development. There can be no
assurance that the Company will achieve or sustain profitability. See "Business
- -- Clinical and Regulatory Status," " -- Third-Party Reimbursement," " --
Competition" and " -- Government Regulation."
 
    FLUCTUATIONS IN OPERATING RESULTS.  The Company anticipates that its results
of operations will fluctuate significantly from quarter to quarter and will
depend upon numerous factors, including actions relating to regulatory and
reimbursement matters, progress and results of clinical trials, the extent to
which the Company's or its competitors' products gain market acceptance,
introduction of alternative means for arterial access site closure and
competitive developments. Due to the elective nature of many coronary
catheterization procedures, patients may defer such procedures during the summer
vacation season. As a result, the Company may experience seasonal fluctuations
in its results of operations, particularly in the second fiscal quarter. Results
of operations will also be affected by the timing of orders received from
distributors, the extent to which the Company is able to expand its
manufacturing capabilities and its international and domestic distribution
networks and the ability of distributors to effectively promote the Company's
products. In addition, depending upon the timing of new product introductions,
competitive factors and warranty claims and product returns, the Company may
need to make allowances for product obsolescence, excess inventory and warranty
claims and product returns. While the Company is currently and will likely
continue making such allowances, there can be no assurance that such allowances
will be adequate to cover all costs associated with such items. See "Business --
Clinical and Regulatory Status," " -- Third-Party Reimbursement," " -- Marketing
and Distribution," " -- Competition" and " -- Government Regulation."
 
    GOVERNMENT REGULATION.  Clinical testing, manufacture, promotion and sale of
the Company's products are subject to extensive regulation by numerous
governmental authorities in the United States, principally the FDA, and
corresponding foreign regulatory agencies. The Federal Food, Drug, and Cosmetic
Act ("FDC Act"), and other federal and state statutes and regulations govern or
influence the testing, manufacture, labeling, advertising, distribution and
promotion of drugs and devices. Noncompliance with applicable requirements can
result in fines, injunctions, civil penalties, recall or seizure of products,
total or partial suspension of production, refusal to authorize the marketing of
new products or to allow the Company to enter into government supply contracts,
and criminal prosecution.
 
                                       7
<PAGE>
    The Company's Prostar and Techstar PVS products are regulated as Class III
medical devices for which FDA approval of a PMA application must be obtained
prior to U.S. commercial sales. A PMA application must be supported by extensive
information, including preclinical and clinical trial data. The PMA process is
expensive, lengthy and uncertain, and a number of products for which PMA
applications have been submitted have never been approved for marketing. In
April 1997, the Company received PMA approval for commercial sale in the United
States of its Prostar 9F and 11F products. In November 1997, the Company
received PMA approval for commercial sale in the United States of its Techstar
6F and Techstar XL 6F products. In June 1997, the Company submitted to the FDA a
PMA supplement for the Prostar Plus 8F and 10F and Prostar XL 8F products for
sale in the United States. There can be no assurance that the Company will be
able to obtain further PMA application or PMA supplement approvals to market its
products, or any other products, on a timely basis, if at all, and delays in
receipt or failure to receive such approvals, the loss of previously received
approvals, or failure to comply with existing or future regulatory requirements
could have a material adverse effect on the Company's business, financial
condition and results of operations.
 
    In August 1997, a competitor of the Company petitioned the FDA for review of
the PMA approval granted to the Prostar 9F and 11F products. The petition was
filed pursuant to a provision of the FDC Act permitting any interested party to
request that the FDA refer an approval order and the basis for the order to an
independent advisory committee of experts, who are to review the information and
provide the FDA with a report and recommendation. Under this provision, the FDA
is required to make public the advisory committee's report and recommendation
and to issue an order either affirming, reversing or modifying the approval. To
the Company's knowledge, the FDA has conducted a review pursuant to this
provision twice since the enactment of the Medical Device Amendments of 1976.
The Company responded to the petition by submitting comments in September 1997
arguing that the FDA should deny it. No assurance can be given that the FDA will
not grant the request to convene an advisory committee to review the PMA
approval granted to the Prostar 9F and 11F products, nor can assurance be given
that the FDA will not, after such review, issue an order reversing or
unfavorably modifying the original PMA approval. Any such action by the FDA
would have a material adverse effect on the Company. Sales of medical devices
outside of the United States are subject to international regulatory
requirements that vary from country to country. The time required to obtain
approval for sale internationally may be longer or shorter than that required
for FDA approval, and the requirements may differ. The Company has obtained the
certifications necessary to enable the CE mark to be affixed to the Company's
Prostar and Techstar products for commercial sales in member countries of the
European Union. The Company has not obtained all other such international
certifications and there can be no assurance it will be able to do so in a
timely manner. The Company has received regulatory approval to market the
Prostar, Prostar Plus, Techstar and Techstar XL products in Japan. The Company,
through its Japanese distributor, intends to commence clinical trials in Japan
that will form the basis of an application for reimbursement approvals in the
Japanese health care system. There can be no assurance Japanese reimbursement
approvals will be obtained in a timely manner or at all. Many other countries in
which the Company currently operates or intends to operate either do not
currently regulate medical devices or have minimal registration requirements;
however, these countries may develop more extensive regulations in the future
that could affect the Company's ability to market its products. In addition,
significant costs and requests for additional information may be encountered by
the Company in its efforts to obtain and maintain regulatory approvals. Any such
events could substantially delay or preclude the Company from marketing its
products in the United States or internationally.
 
    Regulatory approvals, if granted, may include significant limitations on the
indicated uses for which a product may be marketed. In addition, to obtain such
approvals, the FDA and certain foreign regulatory authorities impose numerous
other requirements with which medical device manufacturers must comply. FDA
enforcement policy strictly prohibits the marketing of approved medical devices
for unapproved uses. In addition, product approvals could be withdrawn for
failure to comply with regulatory standards or the occurrence of unforeseen
problems following the initial marketing. The Company will be required to adhere
to the FDA's Quality System Regulation ("QS Reg.") and similar regulations in
other countries,
 
                                       8
<PAGE>
which include testing, control, documentation and other quality assurance
procedures. Ongoing compliance with the QS Reg. and other applicable regulatory
requirements will be monitored through periodic inspections by federal and state
agencies, including the FDA and the California Department of Health Services
("CDHS"), and by comparable agencies in other countries. Failure to comply with
applicable regulatory requirements, including marketing products for unapproved
uses, could result in, among other things, warning letters, fines, injunctions,
civil penalties, recall or seizure of products, total or partial suspension of
production, refusal of the FDA to grant approvals or clearances, withdrawal of
approvals and criminal prosecution. Changes in existing regulations or adoption
of new governmental regulations or policies could prevent or delay regulatory
approval of the Company's products. Certain material changes to medical devices
also are subject to FDA review and clearance or approval. See "Business --
Clinical and Regulatory Status" and " -- Government Regulation."
 
    COMPETITION AND RISK OF TECHNOLOGICAL OBSOLESCENCE.  Competition in the
emerging market for arterial access site closure devices is intense and expected
to increase. The Company believes its principal competition will come from
conventional compression devices and collagen plug closure devices. Conventional
compression products are marketed by several companies that supply C-clamp
closure devices. C.R. Bard, Inc. ("C.R. Bard") markets the Femostop compression
arch device. Datascope Corp. ("Datascope") and Kensey Nash Corporation ("Kensey
Nash") have received PMA approval from the FDA for products that use collagen
plugs to achieve hemostasis. American Home Products Corporation ("American Home
Products") has exclusive worldwide distribution rights to the Kensey Nash
device. Most of the Company's competitors have significantly greater name
recognition, experience, financial, technical, research, marketing, sales,
distribution and other resources than the Company. There can be no assurance
that the Company's competitors will not succeed in developing or marketing
technologies and products that are technologically superior, more effective or
commercially attractive than any that are being developed by the Company, or
that such competitors will not succeed in obtaining regulatory approval,
introducing or commercializing any such products prior to the Company. Such
developments could have a material adverse effect on the Company's business,
financial condition and results of operations. In addition, the medical device
market is generally characterized by rapid and significant technological change
and frequent emergence of new technologies, products and procedures.
Accordingly, the Company's success will also depend in part on its ability to
respond quickly to medical and technological changes. See " -- Fluctuations in
Operating Results" and "Business -- Competition."
 
    LIMITED MANUFACTURING EXPERIENCE AND SCALE-UP RISK.  The Company has only
limited experience in manufacturing the Prostar and Techstar products. The
Company currently manufactures in limited quantities the Prostar and Techstar
products for U.S. clinical trials, limited domestic commercial sales,
international clinical trials and limited international commercial sales. The
Company does not have experience in manufacturing its products in commercial
quantities. Manufacturers often encounter difficulties in scaling up production
of new products, including problems involving production yields, quality control
and assurance, component supply and shortages of qualified personnel, compliance
with FDA regulations, and the need for further FDA approval of new manufacturing
processes. Difficulties encountered by Perclose in manufacturing scale-up could
have a material adverse effect on its business, financial condition and results
of operations. There can be no assurance that future manufacturing difficulties,
which could have a material adverse effect on the Company's business, financial
condition and results of operations, will not occur. See "Business --
Manufacturing" and "-- Government Regulation."
 
    DEPENDENCE UPON KEY SUPPLIERS.  Perclose purchases components used in its
products from various suppliers and relies on single sources for several
components. For certain of these components, there are relatively few
alternative sources of supply. Establishing additional or replacement suppliers
for any of the components used in the Company's products, if required, may not
be accomplished quickly and could involve significant additional costs. Any
supply interruption from vendors or failure of the Company to obtain alternative
vendors, if required, for any of the components used to manufacture the
 
                                       9
<PAGE>
Company's products would limit the Company's ability to manufacture its products
and could therefore have a material adverse effect on the Company's business,
financial condition and results of operations. See "Business -- Manufacturing."
 
    UNCERTAINTY RELATING TO NEW PRODUCT DEVELOPMENT.  The Company's strategy
involves the design and development of new products designed to allow cardiac
surgeons to automate the rapid placement of sutures in blood vessels during CABG
surgery. The product development process is time-consuming and costly, and there
can be no assurance that product development will be successfully completed,
that necessary regulatory clearances or approvals will be granted by the FDA on
a timely basis, or at all, or that the potential products will achieve market
acceptance. Failure by the Company to develop, obtain necessary regulatory
clearances or approvals for, or successfully market potential new products could
have a material adverse effect on the Company's business, financial condition
and results of operations. See "Business -- Research and Development."
 
    DEPENDENCE UPON INTERNATIONAL OPERATIONS AND SALES.  Prior to 1997, all of
the Company's product sales were derived from export sales to international
distributors, none of which are affiliated with the Company. The Company markets
and sells its products outside the United States through a network of
international distributors, and the Company's international sales are largely
dependent on the marketing efforts of, and sales by, these distributors. Sales
through distributors are subject to several risks, including the risk of
financial instability of distributors, the risk of manufacturing and quality
control problems with contract manufacturers and the risk that distributors will
not effectively promote the Company's products. Loss or termination of
distribution relationships could have a material adverse affect on the Company's
international sales efforts and could result in the Company repurchasing unsold
inventory from former distributors by virtue of local laws applicable to
distribution relationships, provisions of distribution agreements or negotiated
settlements entered into with such distributors. In addition, a number of risks
are inherent in international operations and transactions. International sales
and operations may be limited or disrupted by the imposition of government
controls, export license requirements, political instability, trade
restrictions, changes in tariffs, difficulties in staffing, coordinating
communications among and managing international operations. Additionally, the
Company's business, financial condition and results of operations may be
adversely affected by fluctuations in international currency exchange rates as
well as increases in duty rates, difficulties in obtaining export licenses,
constraints on its ability to maintain or increase prices, and competition.
There can be no assurance that the Company will be able to successfully
commercialize the Prostar or Techstar products or any future product in any
international market. See "Business -- Marketing and Distribution."
 
    LIMITED SALES AND MARKETING EXPERIENCE.  The Company has only limited
experience marketing and selling the Prostar and Techstar products, and does not
have experience marketing and selling its products in commercial quantities. The
Company currently has a limited network of distributors that cover certain
European and Pacific Rim countries. In 1997, the Company established a direct
sales force in the United States. Establishing marketing and sales capability
sufficient to support sales in commercial quantities will require significant
resources, and there can be no assurance that the Company will be able to
obtain, train and retain direct sales personnel or that future sales efforts of
the Company will be successful. See "Business -- Marketing and Distribution."
 
    RELIANCE ON PATENTS AND PROTECTION OF PROPRIETARY TECHNOLOGY.  The Company's
ability to compete effectively will depend in part on its ability to develop and
maintain proprietary aspects of its technology. There can be no assurance that
the Company's issued patents, any patents that may be issued as a result of the
Company's U.S. or international patent applications, or the patent under which
the Company has license rights, will offer any degree of protection. There can
be no assurance that any patents that may be issued or licensed to the Company
or any of the Company's patent applications will not be challenged, invalidated
or circumvented in the future. In addition, there can be no assurance that
competitors, many of which have substantial resources and have made substantial
investments in competing technologies, will not seek to apply for and obtain
patents that will prevent, limit or interfere with the Company's ability to
make, use or sell its products either in the United States or in international
markets.
 
                                       10
<PAGE>
    The medical device industry has been characterized by extensive litigation
regarding patents and other intellectual property rights, and companies in the
medical device industry have employed intellectual property litigation to gain a
competitive advantage. There can be no assurance that the Company will not in
the future become subject to patent infringement claims and litigation or
interference proceedings declared by the United States Patent and Trademark
Office ("USPTO") to determine the priority of inventions. The defense and
prosecution of intellectual property suits, USPTO interference proceedings and
related legal and administrative proceedings are both costly and time consuming.
Litigation may be necessary to enforce patents issued to the Company, to protect
trade secrets or know-how owned by the Company or to determine the
enforceability, scope and validity of the proprietary rights of others.
 
    Any litigation or interference proceedings will result in substantial
expense to the Company and significant diversion of effort by the Company's
technical and management personnel. An adverse determination in litigation or
interference proceedings to which the Company may become a party could subject
the Company to significant liabilities to third parties or require the Company
to seek licenses from third parties. Although patent and intellectual property
disputes in the medical device area have often been settled through licensing or
similar arrangements, costs associated with such arrangements may be substantial
and could include ongoing royalties. Furthermore, there can be no assurance that
necessary licenses would be available to the Company on satisfactory terms if at
all. Adverse determinations in a judicial or administrative proceeding or
failure to obtain necessary licenses could prevent the Company from
manufacturing and selling its products, which would have a material adverse
effect on the Company's business, financial condition and results of operations.
 
    In addition to patents, the Company relies on trade secrets and proprietary
know-how, which it seeks to protect, in part, through appropriate
confidentiality and proprietary information agreements. These agreements
generally provide that all confidential information developed or made known to
the individual by the Company during the course of the individual's relationship
with the Company, is to be kept confidential and not disclosed to third parties,
expect in specific circumstances. The agreements generally provide that all
inventions conceived by the individual in the course of rendering services to
the Company shall be the exclusive property of the Company; however, certain of
the Company's agreements with consultants, who typically are employed on a
full-time basis by academic institutions or hospitals, do not contain assignment
of invention provisions. There can be no assurance that proprietary information
or confidentiality agreements with employees, consultants and others will not be
breached, that the Company would have adequate remedies for any breach, or that
the Company's trade secrets will not otherwise become known to or independently
developed by competitors. See "Business -- Patents and Proprietary Rights."
 
    UNCERTAINTY OF THIRD-PARTY REIMBURSEMENT.  In the United States, health care
providers, such as hospitals and physicians that purchase medical devices such
as the Company's products, generally rely on third-party payors, principally
federal Medicare, state Medicaid and private health insurance plans, to
reimburse all or part of the cost of therapeutic and diagnostic catheterization
procedures. Reimbursement for catheterization procedures performed using devices
that have received FDA approval has generally been available in the United
States. The Company anticipates that in a prospective payment system, such as
the disease related group ("DRG") system utilized by Medicare, and in many
managed care systems used by private health care payors, the cost of the
Company's products will be incorporated into the overall cost of the procedure
and that there will be no separate, additional reimbursement for the Company's
products. Furthermore, the Company could be adversely affected by changes in
reimbursement policies of governmental or private health care payors,
particularly to the extent any such changes affect reimbursement for therapeutic
or diagnostic catheterization procedures in which the Company's products are
used. Failure by physicians, hospitals and other users of the Company's products
to obtain sufficient reimbursement from health care payors for procedures in
which the Company's products are used or adverse changes in governmental and
private third-party payors' policies toward reimbursement for such procedures
would have a material adverse effect on the Company's business, financial
condition and results of operations.
 
                                       11
<PAGE>
    In international markets, market acceptance of the Company's products may be
dependent in part upon the availability of reimbursement within prevailing
health care payment systems. However, in general, hospitals using the Company's
products do not receive specific, cost-based, direct reimbursement for the use
of Perclose PVS products. Reimbursement and health care payment systems in
international markets vary significantly by country. Failure of the Company to
receive international reimbursement approvals could have an adverse effect on
market acceptance of the Company's products in the international markets in
which such approvals are sought. See "Business -- Third-Party Reimbursement."
 
    RISK OF INADEQUATE FUNDING.  The Company plans to continue to expend
substantial funds for clinical trials in support of regulatory and reimbursement
approvals, expansion of sales and marketing activities, research and
development, and establishment of commercial-scale manufacturing capabilities.
The Company may be required to expend extra funds if unforeseen difficulties
arise in the course of expansion of manufacturing and marketing activities,
clinical trials of products, obtaining necessary regulatory and reimbursement
approvals or in other aspects of the Company's business. Although the Company
believes that its current cash balances (including the net proceeds from this
offering) and cash generated from the future sale of products will be sufficient
to meet the Company's operating and capital requirements through fiscal 1999,
there can be no assurance that the Company will not require additional financing
within this time frame. The Company's future liquidity and capital requirements
will depend upon numerous factors, including the progress of the Company's
clinical trials, actions relating to regulatory and reimbursement matters, the
costs and timing of expansion of marketing, sales, manufacturing and product
development activities, the extent to which the Company's products gain market
acceptance, and competitive developments. Any additional required financing may
not be available on satisfactory terms, if at all. Future equity financings may
result in dilution to the holders of the Company's Common Stock. See "Use of
Proceeds"
 
    PRODUCT LIABILITY AND RECALL RISK; LIMITED INSURANCE COVERAGE.  The
manufacture and sale of medical products entail significant risk of product
liability claims or product recalls. There can be no assurance that the
Company's existing insurance coverage limits are adequate to protect the Company
from any liabilities it might incur in connection with the clinical trials or
sales of its products. In addition, the Company may require increased product
liability coverage as its products are commercialized. Such insurance is
expensive and in the future may not be available on acceptable terms, if at all.
A successful product liability claim or series of claims brought against the
Company in excess of its insurance coverage, or a recall of the Company's
products, could have a material adverse effect on the Company's business,
financial condition and results of operations. See "Business -- Product
Liability and Insurance."
 
    DEPENDENCE UPON KEY PERSONNEL.  The Company is dependent upon a number of
key management and technical personnel. The loss of the services of one or more
key employees would have a material adverse effect on the Company. The Company's
success will depend on its ability to attract and retain additional highly
qualified management and technical personnel. The Company faces intense
competition for qualified personnel, many of whom are often subject to competing
employment offers, and there can be no assurance that the Company will be able
to attract and retain such personnel. Furthermore, the Company relies on the
services of several medical and scientific consultants, all of whom are employed
on a full-time basis by hospitals or academic or research institutions. Such
consultants are therefore not available to devote their full time or attention
to the Company's affairs. See "Business -- Employees" and "Management."
 
    BROAD DISCRETION OF MANAGEMENT TO ALLOCATE OFFERING PROCEEDS.  The Company
expects that the proceeds of this offering will be used to fund capital
expenditures relating to expanding manfacturing capacity, leasehold improvements
to facilities, expansion of product development activities, working capital
needs and for general corporate purposes. The Company is not currently able to
estimate precisely the allocation of the proceeds among such uses, and the
timing and amount of expenditures
 
                                       12
<PAGE>
will vary depending upon numerous factors. The Company's management will have
broad discretion to allocate the proceeds of this offering and to determine the
timing of expenditures. See "Use of Proceeds."
 
    POSSIBLE VOLATILITY OF STOCK PRICE.  The stock market has recently and from
time to time experienced significant price and volume fluctuations that are
unrelated to the operating performance of particular companies. These broad
market fluctuations may adversely affect the market price of the Company's
Common Stock. In addition, the market price of the shares of Common Stock is
likely to be highly volatile. Factors such as fluctuations in the Company's
operating results, announcements of technological innovations or new products by
the Company or its competitors, FDA and international regulatory actions,
actions with respect to reimbursement matters, developments with respect to
patents or proprietary rights, public concern as to the safety of products
developed by the Company or others, changes in health care policy in the United
States and internationally, changes in stock market analyst recommendations
regarding the Company, other medical device companies or the medical device
industry generally and general market conditions may have a significant effect
on the market price of the Common Stock.
 
    EFFECT OF CERTAIN CHARTER AND BYLAW PROVISIONS.  Certain provisions of the
Company's Certificate of Incorporation and Bylaws may have the effect of making
it more difficult for a third party to acquire, or of discouraging a third party
from attempting to acquire, control of the Company. Such provisions could limit
the price that certain investors might be willing to pay in the future for
shares of the Company's Common Stock. Certain of these provisions allow the
Company to issue Preferred Stock without any vote or further action by the
stockholders, provide for a classified board of directors, eliminate the right
of stockholders to act by written consent without a meeting and eliminate
cumulative voting in the election of directors. These provisions may make it
more difficult for stockholders to take certain corporate actions and could have
the effect of delaying or preventing a change in control of the Company.
 
    SHAREHOLDER RIGHTS PLAN; ISSUANCE OF PREFERRED STOCK.  The Board of
Directors of the Company adopted a Shareholder Rights Plan in January 1997 (the
"Rights Plan"). Pursuant to the Rights Plan, the Board declared a dividend of
one Preferred Stock Purchase Right per share of Common Stock (the "Rights") and
each such Right has an exercise price of $100.00 per one-thousandth of a
Preferred Share (total exercise price of $100,000 per whole share). The Rights
become exercisable upon the occurrence of certain events, including the
announcement of a tender offer or exchange offer for the Company's Common Stock
or the acquisition of a specified percentage of the Company's Common Stock by a
third party. The exercise of the Rights could have the effect of delaying,
deferring or preventing a change in control of the Company, including, without
limitation, discouraging a proxy contest or making more difficult the
acquisition of a substantial block of the Company's Common Stock. These
provisions could also limit the price that investors might be willing to pay in
the future for shares of the Company's Common Stock. The Board of Directors has
the authority to issue up to 30,000 shares of Series A Participating Preferred
Stock and has determined the powers, preferences and rights and the
qualifications, limitations or restrictions granted to or imposed upon such
shares. The Preferred Stock could be issued with voting, liquidation, dividend
and other rights superior to those of the holders of Common Stock. The issuance
of Preferred Stock under certain circumstances could have the effect of
delaying, deferring or preventing a change in control of the Company.
 
    IMMEDIATE AND SUBSTANTIAL DILUTION.  Purchasers of shares of Common Stock in
this offering will incur immediate and substantial dilution in the net tangible
book value of their purchased shares of Common Stock (approximately $21.46 per
share, at an assumed offering price of $25.75 per share). Investors may also
experience additional dilution as a result of the exercise of outstanding stock
options.
 
    NO DIVIDENDS.  The Company has never paid any cash dividends on its Common
Stock and does not anticipate paying such dividends for the foreseeable future.
See "Price Range of Common Stock and Dividend Policy."
 
                                       13
<PAGE>
                                  THE COMPANY
 
    Perclose was incorporated in California in March 1992 and reincorporated in
Delaware in October 1995. Unless the context otherwise requires, references in
this Prospectus to "Perclose" and the "Company" refer to Perclose, Inc., a
Delaware corporation, and where applicable, its California predecessor. The
Company's principal executive offices are located at 199 Jefferson Drive, Menlo
Park, California 94025. Its telephone number is (650) 473-3100.
 
                                USE OF PROCEEDS
 
    The net proceeds to the Company from the sale of the 1,000,000 shares of
Common Stock offered hereby at the public offering price of $25.75 per share are
estimated to be $23,855,000 ($27,485,750 if the over-allotment option is
exercised in full) after deducting the underwriting discount and the estimated
expenses of the offering.
 
    The Company expects to use a majority of the net proceeds to fund capital
expenditures relating to expanding manufacturing capacity, leasehold
improvements to facilities, expansion of product development activities, working
capital needs and general corporate purposes. The amounts actually expended for
each purpose and the timing of such expenditures may vary significantly
depending upon numerous factors, including the progress of the Company's
clinical trials, actions relating to regulatory and reimbursement matters, the
costs and timing of expansion of marketing, sales, manufacturing and product
development activities, the extent to which the Company's products gain market
acceptance and competition. Pending such uses, the Company intends to invest the
net proceeds of this offering in short-term, interest-bearing, investment grade
securities.
 
                PRICE RANGE OF COMMON STOCK AND DIVIDEND POLICY
 
    Since November 8, 1995, the Company's Common Stock has been quoted on the
Nasdaq National Market under the symbol "PERC". The following table sets forth,
for each quarterly period indicated, the high and low sales price for the Common
Stock as reported by the Nasdaq National Market.
 
<TABLE>
<CAPTION>
                                                                                  HIGH        LOW
                                                                                --------    -------
<S>                                                                             <C>         <C>
FISCAL YEAR ENDED MARCH 31, 1996
  Third Quarter (beginning November 8, 1995)................................... $19 1/8     $12 3/4
  Fourth Quarter...............................................................  26 1/4      15
FISCAL YEAR ENDED MARCH 31, 1997
  First Quarter................................................................  24 3/4      20 1/2
  Second Quarter...............................................................  23 1/4      13
  Third Quarter................................................................  24 1/4      16
  Fourth Quarter...............................................................  28 1/2      19
FISCAL YEAR ENDING MARCH 31, 1998
  First Quarter................................................................  27 1/4      20
  Second Quarter...............................................................  27 3/8      20 3/4
  Third Quarter (through November 5, 1997).....................................  26 13/16    22
</TABLE>
 
    The Company has not paid any cash dividends since its inception and does not
anticipate paying any dividends in the foreseeable future.
 
                                       14
<PAGE>
                                 CAPITALIZATION
 
    The following table sets forth the capitalization of the Company as of
September 30, 1997, and as adjusted to reflect the sale of the 1,000,000 shares
of Common Stock offered by the Company hereby (at the assumed public offering
price of $23.50 per share) and the receipt of the estimated net proceeds
therefrom by the Company after deducting the estimated underwriting discounts
and commissions and offering expenses.
 
<TABLE>
<CAPTION>
                                                                                            SEPTEMBER 30, 1997
                                                                                         ------------------------
                                                                                           ACTUAL    AS ADJUSTED
                                                                                         ----------  ------------
                                                                                              (IN THOUSANDS)
<S>                                                                                      <C>         <C>
Stockholders' equity:
  Preferred Stock: $.001 par value, 5,000,000 shares authorized, actual and as
    adjusted; none issued and outstanding, actual and as adjusted......................  $   --       $   --
  Common Stock: $.001 par value, 30,000,000 shares authorized, 9,627,497 shares issued
    and outstanding actual, 10,627,497 shares issued and outstanding, as adjusted(1)...          10           11
  Additional paid-in capital...........................................................      58,798       82,652
  Accumulated deficit..................................................................     (36,328)     (36,328)
  Deferred compensation................................................................        (734)        (734)
                                                                                         ----------  ------------
    Total stockholders' equity.........................................................  $   21,746   $   45,601
                                                                                         ----------  ------------
                                                                                         ----------  ------------
</TABLE>
 
- ---------
 
(1) Excludes 1,390,773 shares of Common Stock subject to outstanding options
    granted pursuant to the Company's stock option plans as of September 30,
    1997 at a weighted average exercise price of $15.44 per share.
 
                                       15
<PAGE>
                            SELECTED FINANCIAL DATA
 
    The statements of operations data presented below for the period from
inception (March 24, 1992) through March 31, 1993 and for each of the four years
in the period ended March 31, 1997 and with respect to the balance sheet data as
of March 31, 1993, 1994, 1995, 1996 and 1997 is derived from financial
statements of the Company not included herein that have been audited by Ernst &
Young LLP, independent auditors. The statements of operations data for the
six-month periods ended September 30, 1996 and 1997 and with respect to the
balance sheet data as of September 30, 1997 is derived from unaudited financial
statements not included herein and include, in the opinion of the Company, all
adjustments (consisting only of normal recurring adjustments) necessary for a
fair presentation of the Company's results of operations for those periods and
financial position at that date. The results for the six months ended September
30, 1997 are not necessarily indicative of the results for any future period.
The Company has not paid any cash dividends on its Common Stock or Preferred
Stock. The selected financial data set forth below is qualified in its entirety
by, and should be read in conjunction with, "Management's Discussion and
Analysis of Financial Condition and Results of Operations" and the financial
statements and notes thereto not included in this Prospectus.
 
<TABLE>
<CAPTION>
                                                                                                                SIX MONTHS ENDED
                                                  INCEPTION TO              YEARS ENDED MARCH 31,                SEPTEMBER 30,
                                                    MARCH 31,     ------------------------------------------  --------------------
                                                      1993          1994       1995       1996       1997       1996       1997
                                                 ---------------  ---------  ---------  ---------  ---------  ---------  ---------
                                                                     (IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)
<S>                                              <C>              <C>        <C>        <C>        <C>        <C>        <C>
STATEMENTS OF OPERATIONS DATA:
  Net revenues.................................     $  --         $  --      $     178  $   2,457  $   4,456  $   2,535  $   2,380
  Operating expenses:
    Cost of goods sold, including manufacturing
      start-up costs...........................        --               136      2,149      4,772      4,703      2,223      3,249
    Research and development...................           411         1,595      3,066      3,059      4,745      2,395      2,525
    Marketing, general and administrative......           204           945      2,155      3,486      6,301      2,496      5,581
                                                       ------     ---------  ---------  ---------  ---------  ---------  ---------
    Total operating expenses...................           615         2,676      7,370     11,317     15,749      7,114     11,355
                                                       ------     ---------  ---------  ---------  ---------  ---------  ---------
  Loss from operations.........................          (615)       (2,676)    (7,192)    (8,860)   (11,293)    (4,579)    (8,975)
  Interest and other income....................            18            66        258        941      1,753        954        705
  Interest expense.............................            (9)          (14)       (59)      (165)      (117)       (64)       (92)
                                                       ------     ---------  ---------  ---------  ---------  ---------  ---------
  Loss before income taxes.....................           606        (2,624)    (6,993)    (8,084)    (9,657)    (3,689)    (8,362)
  Provision for income taxes...................             1        --         --         --         --         --         --
                                                       ------     ---------  ---------  ---------  ---------  ---------  ---------
    Net loss...................................     $    (607)    $  (2,624) $  (6,993) $  (8,084) $  (9,657) $  (3,689) $  (8,362)
                                                       ------     ---------  ---------  ---------  ---------  ---------  ---------
                                                       ------     ---------  ---------  ---------  ---------  ---------  ---------
  Net loss per share...........................                                         $   (1.34) $   (1.01) $   (0.39) $   (0.87)
  Shares used in computing net loss per
    share......................................                                             6,025      9,517      9,498      9,598
  Pro forma net loss per share.................                              $   (1.04)
  Shares used in computing pro forma net loss
    per share..................................                                  6,717
</TABLE>
 
<TABLE>
<CAPTION>
                                                                            MARCH 31,
                                                      -----------------------------------------------------  SEPTEMBER 30,
                                                        1993       1994       1995       1996       1997          1997
                                                      ---------  ---------  ---------  ---------  ---------  --------------
                                                                                 (IN THOUSANDS)
<S>                                                   <C>        <C>        <C>        <C>        <C>        <C>
BALANCE SHEET DATA:
  Cash, cash equivalents and short-term
    investments.....................................  $   1,441  $   5,540  $   8,127  $  37,857  $  27,673    $   17,983
  Total assets......................................      1,613      6,386     10,949     40,916     32,514        24,643
  Long-term debt and capital lease obligations, less
    current portion.................................     --            174        593        511        128        --
  Accumulated deficit...............................       (608)    (3,232)   (10,225)   (18,437)   (28,044)      (36,328)
  Total stockholders' equity........................      1,507      5,725      9,041     38,500     29,382        21,746
</TABLE>
 
                                       16
<PAGE>
                                    BUSINESS
 
THE COMPANY
 
    Perclose designs, develops, manufactures and markets minimally invasive
medical devices that automate the delivery of needles and sutures for the
surgical closure of arterial access sites in coronary catheterization
procedures. The Company is also developing devices for the connection of blood
vessels in conventional and minimally invasive coronary artery bypass graft
("CABG") procedures. The Company's first products, the Prostar and Techstar
products, are a family of devices that surgically close arterial access sites
after catheterization procedures such as angioplasty, stenting, atherectomy and
angiography, termed percutaneous vascular surgery ("PVS"). The Prostar and
Techstar PVS products are designed to provide routine, definitive closure that
replicates results previously obtainable only through open surgery, without the
associated risks and costs. Randomized clinical trials of the Prostar and
Techstar products have demonstrated significant clinical and economic advantages
over conventional compression methods of arterial access site closure. These
advantages include achieving rapid hemostasis (the cessation of bleeding),
reducing nursing time required to monitor patients, allowing earlier patient
ambulation and discharge, enabling more efficient use of the catheterization
laboratory, reducing overall treatment costs and improving patient comfort. In
addition, for certain high risk patients, such as those who have experienced a
heart attack, the Company's products allow continuation of aggressive
anticoagulation, thrombolytic or anti-restenosis drug therapy without increasing
the risk of bleeding complications at the arterial access site.
 
    The Company commenced international shipments of its first Prostar and
Techstar products in December 1994 and July 1995, respectively. In April 1997,
the Company received FDA Premarket Approval ("PMA") for commercial sale in the
United States of the initial Prostar products. In November 1997, the Company
received PMA supplement approval for commercial sale in the United States of its
initial Techstar and Techstar XL products. In June 1997, the Company submitted
to the FDA a PMA supplement seeking approval for commercial sale in the United
States of certain Prostar Plus and Prostar XL products.
 
    Industry estimates in 1997 indicate that therapeutic and diagnostic coronary
catheterizations represent approximately 3.5 million procedures annually
worldwide, including approximately 2.1 million in the United States. Of the 3.5
million total procedures, approximately 675,000 are therapeutic procedures, of
which approximately 425,000 occur in the United States. Of the remaining
approximately 2.9 million diagnostic procedures, approximately 1.7 million occur
in the United States.
 
    The Company is also developing the Heartflo anastomosis system to allow
cardiac surgeons to automate the rapid placement of sutures in blood vessels
during CABG surgery. The success of a CABG procedure is largely determined by
the quality of the anastomosis (attachment), which dictates the long-term
patency, or blood flow, through the vein graft to the coronary arteries. While
cardiac surgeons have developed effective surgical techniques to perform
hand-sewn anastomoses of coronary blood vessels in conventional CABG surgeries,
the recent emergence of minimally invasive CABG procedures introduces additional
challenges for performing hand-sewn anastomoses during such procedures. Since
the opening to the chest cavity created by ports or mini-thoracotomies used in
minimally invasive CABG procedures is small, accessing and suturing the bypass
graft to the coronary artery is more difficult, may take longer to perform and
may not achieve the same therapeutic results as in conventional open chest CABG
surgery. The Heartflo system is being designed to replicate an ideal suture
pattern in a rapid and automated fashion while still allowing the surgeon
ultimate control over the tensioning and tying of the sutures to complete
attachment of the bypass graft. The Heartflo system is being designed for use
with conventional, open chest CABG procedures and the newer, minimally invasive,
beating heart and stopped heart procedures. The Heartflo system is currently
undergoing preclinical testing. Industry estimates in 1997 indicate that there
are approximately 540,000 CABG procedures performed annually worldwide, with
320,000 of those occurring in the United States.
 
    The Company's objectives are to become the leader in the design, development
and commercialization of suture-based closure devices, to establish percutaneous
vascular surgery using the Company's
 
                                       17
<PAGE>
products as the standard of care for post-catheterization arterial access site
management and to commercialize new devices based on the Company's core
technology that improve clinical outcomes and reduce costs. Key elements of the
Company's strategy include demonstrating the clinical and cost advantages of its
products over conventional closure methods, extending the Company's technology
platform and expanding the markets for its existing products. The Company also
plans to develop additional versions of its products for new and emerging
catheterization procedures, including procedures involving large diameter
catheter devices where arterial access site closure can be particularly
difficult.
 
INDUSTRY OVERVIEW
 
    THERAPEUTIC INTERVENTIONAL CARDIOLOGY MARKET
 
    CORONARY ARTERY DISEASE.  More than 6 million people in the United States
have been diagnosed with coronary artery disease, which is a formation of
atherosclerotic plaque that causes blood flow restrictions, or blockages, within
the coronary arteries. These blockages can occur anywhere within the complex
network of arteries that provide blood to the heart muscle. If left untreated,
coronary artery disease can cause severe chest pain and lead to heart attacks.
The principal means of treating coronary artery disease if diet, exercise or
drug therapy fail to achieve therapeutic results include CABG, a highly invasive
open surgical procedure, and percutaneous transluminal coronary angioplasty
("balloon angioplasty") as well as other percutaneous catheter-based procedures
including stenting and atherectomy. Prior to the late 1970's, CABG was the only
alternative for treating coronary artery disease that failed to respond to
non-invasive therapy. Since its clinical introduction in 1978, balloon
angioplasty, either alone or in conjunction with stents, has emerged as the
principal less invasive alternative to CABG. Industry estimates in 1997 indicate
that there are approximately 540,000 CABG procedures performed annually
worldwide, with 320,000 of those occurring in the United States. Industry
sources estimate that there are approximately 675,000 balloon angioplasty,
stenting and atherectomy procedures performed annually worldwide, including
approximately 425,000 such procedures in the United States. In addition,
minimally invasive forms of CABG have been recently introduced and continue to
be developed. These procedures attempt to reduce the invasiveness of CABG by
minimizing the size of the incisions required.
 
    BALLOON ANGIOPLASTY AND STENTING PROCEDURE.  At the beginning of a balloon
angioplasty procedure, the physician initiates anticoagulation drug therapy to
prevent formation of blood clots which can cause arterial blockages.
Anticoagulation therapy is typically continued throughout the procedure. A local
anesthetic is administered and a small incision is made in the groin area to
gain access to the femoral artery, which is punctured to create an access site
for catheterization devices. The cardiologist inserts an introducer sheath into
the femoral artery and places a guiding catheter through the introducer sheath
to create a path from outside the patient to the arteries of the heart. The
cardiologist advances a small guidewire through the inside of the guiding
catheter, into the coronary artery and across the site of the blockage. A
balloon catheter is delivered over the guidewire through the inside of the
guiding catheter into the artery and across the site of the blockage. The
balloon is inflated to compress the blockage against the walls of the artery,
thereby enlarging the diameter of the arterial lumen and increasing blood flow
to the heart muscle. During this procedure, anticoagulation drug therapy is
ordinarily used to prevent clot formation in the coronary arteries. At the
conclusion of the procedure, the cardiologist decides if the benefits of
continued anticoagulation therapy outweigh the increased risk of bleeding at the
femoral artery access site. This decision influences the level of post-procedure
nursing observation and the length of the hospital stay, which is typically one
to three days.
 
    Other catheter-based therapeutic coronary procedures include stenting and
atherectomy. Stents are implantable, metal, tube shaped devices delivered on a
balloon catheter and permanently deployed at a blockage site to maintain
increased lumen diameter by mechanically supporting the artery. Stenting
procedures have been reported to reduce the risk of abrupt coronary artery
closure, thereby creating the possibility for outpatient stenting due to a
reduced need to keep patients under post-procedure nursing observation. The
current potential for outpatient stenting is, however, limited by the inability
to achieve predictable, sustained hemostasis of the arterial access site.
Atherectomy encompasses several types of devices that are designed to remove
atherosclerotic plaque that blocks blood flow in the arteries.
 
                                       18
<PAGE>
    DIAGNOSTIC ANGIOGRAPHY AND OTHER PERCUTANEOUS VASCULAR PROCEDURES
 
    Patients believed to have coronary artery disease typically undergo
diagnostic angiography to determine the extent and location of their arterial
blockages. Angiography is a procedure in which radiopaque dye visible under
x-ray is delivered through a catheter directly into the coronary arteries,
allowing real-time visualization with an x-ray imaging system. Like therapeutic
angioplasty, angiography is also performed using a catheter placed into the
vascular system through a puncture in the femoral artery. Industry estimates in
1997 indicate that angiography is performed annually on approximately 2.9
million patients worldwide including approximately 1.7 million patients in the
United States. Angiography procedures represent a significant market opportunity
for arterial closure devices because under conventional treatment protocols,
many of these patients are kept under nursing observation for several hours
following the procedure primarily to confirm achievement of hemostasis.
 
    Many other catheterization procedures rely on percutaneous access to the
vascular system through a puncture in the femoral artery. These procedures
include peripheral vascular therapeutic and diagnostic procedures, of which
approximately 1.0 million and 1.3 million, respectively, are performed annually
worldwide. These procedures may represent a significant market opportunity for
arterial closure devices because under conventional treatment protocols, many of
these patients are kept under nursing observation following the procedure
primarily to confirm achievement of hemostasis. Therefore, the availability of
reliable arterial access site closure devices could facilitate early discharge
of these patients. Percutaneous vascular surgery devices could also be used to
close femoral artery access sites in interventional neuroradiology
catheterization procedures, electrophysiology procedures to map and ablate
cardiac arrhythmias and intra-aortic balloon pump procedures. In addition,
emerging percutaneous catheterization procedures and other new interventional
procedures, including catheter-based vascular grafts, cardiopulmonary support
procedures and percutaneous treatment of abdominal aortic aneurysms, may also
represent new market opportunities for larger versions of the Company's PVS
products.
 
ARTERIAL ACCESS SITE MANAGEMENT
 
    Following catheter-based coronary procedures such as balloon angioplasty,
stenting, atherectomy or angiography, the physician or nursing staff must close
the arterial access site. With procedures relying on conventional compression
closure techniques, anticoagulation therapy (which is used in all interventional
cases) is discontinued for up to four hours prior to closure of the access site
to allow the patient's clotting function to normalize. During this period, the
introducer sheath is left in place and the patient must remain immobile in bed
to prevent bleeding at the access site. Once the introducer sheath is removed,
intense direct pressure is applied to the puncture site for a period of time
ranging from 15 minutes to over one hour to facilitate formation of a blood clot
in order to seal the arterial access site. This pressure is applied either
manually or with a large C-clamp or other pressure device placed around the
patient's leg. A dislodged clot can result in internal or external bleeding,
which may necessitate transfusions or result in other vascular complications if
not immediately controlled. Because any movement may dislodge the clot, the
patient is required to remain immobile under close nursing observation in a
coronary care unit for an additional four to 24 hours after the procedure,
depending on the amount of anticoagulation drug therapy used and the type of
procedure performed. Conventional closure methods may result in substantial
costs, limit operating efficiencies and constrain the scheduling and usage of
the catheterization laboratory by the number of beds and nursing staff in the
coronary care unit.
 
    The arterial access site can be affected by other complications associated
with conventional compression methods, including a hematoma in which a
coagulated blood mass forms at the access site, a pseudoaneurysm in which blood
continues to flow from the artery into the coagulated blood mass at the access
site, femoral nerve damage from extended compression, and a vagal response
characterized by a sharp drop in blood pressure. Patients often experience
significant pain and discomfort during compression of the artery and in the
period in which they are required to be immobile, and may require pain
medication. Many patients report that the pain associated with compression of
the artery and immobilization is the most uncomfortable and difficult aspect of
the catheterization procedure.
 
                                       19
<PAGE>
    In addition to the anticoagulation therapy administered during routine
coronary catheterization procedures, post-procedure anticoagulation or
antiplatelet therapy is necessary in certain patients who are at an elevated
risk of formation of a life-threatening blood clot in the coronary arteries. The
Company believes that this group may represent up to 30% of therapeutic coronary
catheterization patients and includes patients who have experienced a heart
attack or undergone complicated balloon angioplasty characterized by dissection
of the arterial wall during expansion of the balloon. For these patients,
optimal treatment usually requires continued anticoagulation therapy to keep
blood clots from forming, new drugs to reduce the risk of restenosis or
thrombolytic drugs to dissolve existing clots. With conventional arterial access
site closure therapies, the interventional cardiologist is faced with the choice
of discontinuing anticoagulation therapy and closing the arterial access site
using compression or continuing drug therapy and leaving the sheath in place
overnight, which requires the patient to remain immobile and extends the
hospital stay. The cardiologist must therefore manage the difficult balance of
preventing clot formation in the coronary arteries while encouraging a clot
formation to close the arterial access site. In high clinical need patients,
conventional arterial access site management options may lead to a greater risk
of heart attack, higher vascular complication rates, significant patient
discomfort during clamping and immobilization, intensive nursing monitoring,
extended hospitalization and increased costs of care.
 
PERCLOSE PVS SOLUTION
 
    The Company believes that its PVS products, which achieve rapid closure of
arterial access sites following percutaneous catheterization procedures,
overcome the clinical disadvantages of conventional closure methods and enable
catheterization laboratories to achieve increased operating efficiencies and
cost savings. The Company's PVS products enable the physician to suture arterial
access sites percutaneously, providing a means of closure that has previously
been possible only through open vascular surgery. Since the introduction of
catheterization procedures, vascular surgery has been the definitive method used
to close arterial access sites that do not respond to conventional compression
therapy. Open surgery requires a long incision in the patient's groin area,
involves a significant recovery period and increases overall treatment costs.
While surgeons can close the arterial access site with one or two sutures, the
invasive nature of open surgery makes it unsuitable for routine use in
catheterization patients. Perclose PVS products are designed to provide routine,
definitive closure that replicates, through a minimally invasive procedure, the
results previously obtainable only through open surgery without the associated
risks and costs. The products are designed to be easy to use, relying on
standard techniques that are familiar to physicians performing these procedures.
 
    Perclose PVS products are used in the catheterization laboratory to close
the arterial access site as the final step in the catheterization procedure. By
achieving rapid hemostasis, PVS products reduce the need for the patient to
remain immobile under close observation in the coronary care unit. This
minimizes the patient's pain and discomfort and allows the patient to ambulate
shortly after the catheterization procedure. Early ambulation of patients can
also improve utilization of hospital resources. For example, in conventional
practice, angiography is usually performed in the morning to permit same-day
discharge following observation and confirmation of hemostasis. Earlier
ambulation and discharge of these patients may contribute to more efficient
usage of the of catheterization laboratory by allowing scheduling of diagnostic
procedures throughout the day.
 
MINIMALLY INVASIVE CABG SURGERY PRODUCTS
 
    The Company's first application of its core technology and technical
competency outside of the PVS area is the Heartflo anastomosis system for use in
conventional, open chest CABG procedures and the newer minimally invasive
beating heart and stopped heart procedures. The success of a CABG procedure is
largely determined by the quality of the anastomosis (attachment), which
dictates the long-term patency, or blood flow, through the vein graft to the
coronary arteries. While effective surgical techniques enabling cardiac surgeons
to perform hand-sewn anastomoses of coronary blood vessels in conventional
 
                                       20
<PAGE>
CABG surgeries exist, the recent emergence of minimally invasive CABG procedures
introduces additional challenges for hand-sewn anastomoses during such
procedures. Since the opening to the chest cavity created by ports or
mini-thoracotomies used in minimally invasive CABG procedures is small,
accessing and suturing the bypass graft to the coronary artery is more
difficult, may take longer to perform and may not achieve the same therapeutic
results as in conventional open chest CABG surgery.
 
    The Heartflo system is being designed to consistently replicate the ideal,
hand-sewn pattern used by cardiac surgeons during a CABG procedure by
automatically deploying needles and sutures in a precise pattern in both the
bypass vein graft and the coronary artery while still allowing the cardiac
surgeon to maintain control over the joining of the bypass grafts to the
coronary artery. When using the Heartflo system, the surgeon would first deploy
needles and sutures through the bypass graft vessel and then through the
coronary artery. Once the sutures have been deployed by the system, the cardiac
surgeon would then tie the two vessels together using standard surgical knots.
 
    The Company believes that by automating the placement of the sutures, the
pattern and positioning of the sutures will be more precise, consistent and
reliable, leading to more clinically efficacious attachments of vein grafts to
coronary arteries (i.e. higher patency rates). In addition, the Company believes
that by automating the suture placement process, the Heartflo system may reduce
the time needed to perform an anastomosis, especially in minimally invasive CABG
procedures. Finally, by allowing the cardiac surgeon to maintain control of the
final suture tensioning and tying enables the surgeon to make clinical decisions
based upon the anatomy, thickness and calcification of the vessels to be joined.
 
    Most of the recent product development announcements and introductions for
minimally invasive CABG procedures have focused on improving access to the chest
cavity by reducing the need to perform a medial sternotomy during the CABG
procedure. One of the limitations of minimally invasive CABG is the inability to
bypass all blockages of the arteries of the heart. During these less-invasive
procedures, the surgeon has a difficult time rotating the heart to access to all
coronary vessels and is often unable to reach the aorta in order to attach the
proximal end of the graft. The Heartflo system is being designed to facilitate
the attachment of bypass grafts for these more difficult attachments in the
smaller working spaces used in minimally invasive CABG procedures. The Company
believes that the Heartflo system will enable surgeons in the newer minimally
invasive CABG procedures to obtain a quality of anastomosis similar to that
obtained in conventional CABG procedures, whether surgeons perform these newer
procedures through ports or mini-thoracotomies and whether on still or beating
hearts. The Company believes that the availability of tools for improving the
quality of the anastomosis for minimally invasive CABG procedures could
encourage the adoption and enhance the long term effectiveness of these
procedures.
 
    The Company plans to develop three types of anastomosis devices: a proximal
device which would attach one end of the graft to the aorta, a distal
end-to-side device which would attach the distal end of the graft to the
coronary artery, and a distal side-to-side device that would attach the middle
of the graft to a coronary artery.
 
BUSINESS STRATEGY
 
    The Company's objective is to be a leader in the development, manufacture
and marketing of minimally invasive medical devices that automate the delivery
of needles and sutures in cardiovascular surgical procedures. Key elements of
the Company's strategy include:
 
    EMPHASIZE CLINICAL UTILITY AND COST-EFFECTIVENESS.  In five randomized
trials with over 2,000 patients enrolled, the Company has established that
percutaneous vascular surgical repair of the arterial access site decreases time
to hemostasis, ambulation and discharge and improves patient comfort. The
Company uses data collected from clinical trials to demonstrate the clinical and
cost advantages of its products to physicians, administrators and health care
payors.
 
                                       21
<PAGE>
    APPLY FOCUSED MARKETING, SALES AND PHYSICIAN TRAINING.  The Company's
approved products are currently marketed to interventional cardiologists,
radiologists and catheterization laboratory administrators. These products are
currently marketed in the United States through a direct sales organization and
internationally through distributors in Germany, France, Japan and other major
countries, under regulatory approvals where required. The Company believes that
the majority of interventional catheterization procedures in the United States
are performed in high volume catheterization laboratories that can be served
effectively by a relatively small, focused sales force. Perclose develops and
maintains close working relationships with its customers to address their needs
for products and services and to receive input regarding the Company's product
development plans. The Company builds these relationships through focused
physician training, which the Company believes will also be an important factor
in encouraging cardiologists to use the Company's products. Perclose provides a
standardized, in-the-field training course in the markets it enters.
 
    EXTEND THE TECHNOLOGY PLATFORM.  The Company applies its core technology to
other high value cardiovascular surgical areas in which remote and precise
delivery of needles and sutures would improve clinical outcomes and reduce
health care costs. Anastomosis of coronary blood vessels during CABG procedures
represents the first application of the Company's core technology beyond
arterial access site closure. The Company intends to develop new applications
for its technology in other minimally invasive surgical procedures.
 
    EXPAND MARKETS FOR EXISTING PRODUCTS.  The Company believes that several
other minimally invasive catheterization procedures, both currently used and
under development, will be candidates for application of its existing PVS
products. The Company intends to expand its product marketing efforts into these
new clinical applications, including electrophysiology, interventional
neuroradiology and intra-aortic balloon pump procedures, where percutaneous
surgical closure of arterial access sites can meet significant clinical needs
and achieve cost reductions.
 
    MAINTAIN TECHNOLOGICAL LEADERSHIP.  The Company continually evaluates new
developments in percutaneous catheterization procedures and will seek to expand
its product development efforts to address access site closure following these
new procedures, including catheter-based vascular grafts, treatment of abdominal
aortic aneurysms and cardiac pulmonary support procedures. Because the large
diameter catheter devices required for these procedures make closure of the
arterial access site difficult using conventional compression methods, open
surgical procedures are ordinarily used to close the access sites. The Company
believes that larger diameter versions of its current PVS products could be used
to close the arterial access sites in these procedures, making it feasible to
perform such procedures in a less invasive manner. The Company also focuses on
improving the performance and ease of use and reducing the manufacturing costs
of its PVS products.
 
PRODUCTS AND TECHNOLOGY
 
    The Company has introduced two PVS product families, the Techstar and
Prostar. Techstar products are single-suture devices for suturing 6F and 7F
arterial access sites(1). Prostar products provide two sutures for closing
arterial access sites ranging in diameter from 7F to 11F. Products within each
product family can have the added designation of Plus or XL. The Plus and XL
designations signify the second and third generations, respectively, of the
Techstar and Prostar product evolution. The Plus and XL enhancements reduce
procedure time, increase ease of use and reduce manufacturing costs. The XL
series, or third generation design of both the Techstar and Prostar devices, has
reduced procedure time to less than five minutes, compared with over 10 minutes
required for the first generation Prostar devices.
 
    PROSTAR PRODUCTS.  The Prostar products are single-use, hand-held medical
devices which consist of a four-needle, two-suture Prostar PVS device and a
Perclose Knot Pusher. In addition, the 9F and 11F sizes
 
- ------------
 
(1)   Interventional cardiology devices are measured in French sizes,
      abbreviated "F."
 
      One French size is equal to one-third of a millimeter in diameter
      (3F=1mm).
 
                                       22
<PAGE>
require a pre-dilator and a guidewire. Prostar products are currently marketed
internationally in the 8F and 10F sizes and are marketed in the United States in
the 9F and 11F sizes. Prostar products are used to close arterial access sites
following balloon angioplasty, stenting and atherectomy procedures.
 
    At the end of the catheterization procedure, the introducer sheath used in
the procedure is removed utilizing a standard over-the-wire exchange technique.
Next, the flexible sheath of the PVS device is inserted in the artery over a
guidewire (use of the first generation Prostar product requires pre-dilation
prior to insertion of the sheath). The unique design of the device allows the
physician to maintain hemostasis throughout the procedure. The device includes a
marker port in the needle guide, proximal to the tips of the needles. Arterial
blood flow into the marker port indicates that the device has been properly
positioned with the needles and sutures inside the arterial lumen. Once
positioned, the pull handle is drawn away from the patient, deploying the
needles and sutures. As the needles advance toward the artery wall, they are
guided by a ramp that precisely positions the needles around the arterial access
site. The needles are captured in the barrel of the device which also positions
the needles for removal. Two needles, each attached to the end of a single
suture, will create one surgical stitch. The needles are removed from the device
and detached from the sutures which are then tied in a standard surgical square
knot. The device is removed and the knots are advanced to the arterial access
site with the Perclose Knot Pusher. The knots can be further secured with
additional throws, which are also advanced with the Knot Pusher.
 
    TECHSTAR PRODUCTS.  Techstar products consist of a two-needle, single-suture
Techstar PVS device and a Perclose Knot Pusher. Techstar products are currently
marketed internationally in 6F, 7F and 6FS (short) sizes. The Techstar 6F
product is suitable for closure of arterial access sites in therapeutic and
diagnostic procedures having puncture sites dilated by 6F or smaller introducer
sheaths while the 7F diameter product is suitable for closure of puncture sites
dilated by 7F interventional and diagnostic introducer sheaths. The Techstar 6FS
is shorter in length than the Techstar 6F and is suitable for use after
peripheral diagnostic and interventional procedures for vascular disease of the
lower legs.
 
CLINICAL AND REGULATORY STATUS
 
    In April 1997, the Company received PMA approval for commercial sale in the
United States of its Prostar 9F and 11F products. In November 1997, the Company
received PMA supplement approval for commercial sale in the United States of its
Techstar 6F and Techstar XL 6F products. In June 1997, the Company submitted to
the FDA a PMA supplement for the Prostar Plus 8F and 10F and Prostar XL 8F
products for commercial sale in the United States.
 
    Perclose PVS products are currently being marketed internationally in
Germany, France, Japan and other major countries under regulatory approvals
where required. The Company obtained CE mark certification in 1996 which allows
it to market its products in all member countries of the European Union and to
ship its products to European Union countries directly from its United States
manufacturing facility.
 
    The Company has received regulatory approval to market the Prostar and
Techstar products in Japan and has commenced a clinical trial in Japan that will
form the basis for an application for reimbursement approvals in the Japanese
health care system. Getz Brothers Company Ltd., the Company's Japanese
distributor, will be responsible for management of clinical trials, obtaining
reimbursement approval for the Company's products and obtaining and holding
regulatory approvals in Japan. There can be no assurance that such reimbursement
approvals will be obtained in a timely manner or at all. See "Risk Factors --
Government Regulation."
 
                                       23
<PAGE>
MARKETING AND DISTRIBUTION
 
    The Company markets its PVS products in the United States through a direct
sales organization. The Company believes that the majority of interventional
catheterization procedures in the United States are performed in high volume
catheterization laboratories, and that these institutions can be effectively
served by a relatively small, focused sales force. The Company develops and
maintains close working relationships with its customers to address their needs
for products and services and to receive input regarding the Company's product
development plans. The Company builds these relationships through focused
physician training, which the Company believes will also be a key factor in
encouraging physicians to use the Company's products. The Company provides a
standardized, in-the-field training course in the markets it enters.
 
    The Company's international sales and marketing strategy for PVS products
focuses on interventional cardiologists and radiologists through established
distributors in major international markets, subject to required regulatory
approvals. The Company generally operates under written distribution agreements
with its distributors, although the Company does not have written agreements
with certain distributors, typically those in smaller markets. Distributors with
which the Company has distribution agreements generally have the exclusive right
to sell the Company's products within a defined territory. These distributors
also typically market other medical products, although the Company generally
seeks to obtain covenants from its distributors prohibiting them from marketing
medical devices that compete directly with the Company's products. The Company's
distributors typically purchase the Company's products at a discount from the
end user list price and resell the products to hospitals and clinics. Sales to
international distributors are denominated in U.S. dollars, except to the
Company's German and French distributors. The distributor and end-user price
varies from country to country. The Company has seven employees directly
involved with physician training and assisting distributors assigned to European
and Asian territories.
 
    All of the Company's revenues through March 31, 1997 were derived from
export sales to international distributors, primarily in Europe, none of which
are affiliated with the Company. Sales to A.D. Krauth GmbH, Medicorp S.A. and
Getz Brothers Company Ltd., the Company's German, French and Japanese
distributors, respectively, accounted for approximately 59%, 15% and 15%,
respectively, of net sales for the fiscal year ended March 31, 1997. For the six
months ended September 30, 1997, sales to A.D. Krauth GmbH were 14% of net
sales.
 
RESEARCH AND DEVELOPMENT
 
    The Company's research and development activities are performed by an
internal research and development staff. The Company has a three-part strategy
in research and development. First, the Company continues to enhance its
existing PVS products to maintain its technological leadership in percutaneous
vascular surgery. Second, the Company plans to apply its core technology to the
closure of other arterial access sites including those for vascular grafts,
treatment of abdominal aortic aneurysms and cardiac pulmonary support
procedures. Third, the Company is applying its core technology to other high
value surgical areas such as coronary anastomosis with its Heartflo system.
Research and development expenses for fiscal 1995, 1996 and 1997 were $3.1
million, $3.1 million and $4.7 million respectively and were $2.5 million for
the six-month period ending September 30, 1997.
 
MANUFACTURING
 
    The Company currently manufactures its PVS products in a Class 10,000 clean
room facility in Menlo Park, California. The Company purchases components from
various suppliers and relies on single sources for several parts. To date, the
Company has not experienced any significant adverse affects resulting from
shortages of components. Delays associated with any future part shortages,
particularly as the Company scales up its manufacturing activities in support of
commercial sales in the United States and for international distributor orders,
would have a material adverse effect on the Company's business, financial
condition and results of operations. The Company does not have experience in
manufacturing
 
                                       24
<PAGE>
its products in large-scale commercial quantities. Manufacturers often encounter
difficulties in scaling up production of new products, including problems
involving production yields, quality control and assurance, component supply and
lack of qualified personnel. Difficulties encountered by the Company in
manufacturing scale-up could have a material adverse effect on its business,
financial condition and results of operations.
 
    The Company is also required to register as a medical device manufacturer
with the FDA and to list its products with the FDA. As such, the Company is
subject to inspections by the FDA for compliance with the FDA's good
manufacturing practices ("GMP") and other applicable regulations. In addition,
in connection with international sales, the Company is required to comply with
GMP requirements and ISO 9001 standards. These standards require that the
Company maintain processes and documentation in a prescribed manner with respect
to manufacturing, testing and quality control activities. Failure to either
attain or maintain compliance with the applicable regulatory requirements or
standards of various regulatory agencies would have a material adverse effect on
the Company's business, financial condition and results of operations. See "Risk
Factors -- Limited Manufacturing Experience and Scale-Up Risk."
 
COMPETITION
 
    Competition in the emerging market for arterial access site closure devices
is intense and is expected to continue to increase. The Company believes its
principal competition will come from conventional manual compression devices,
mechanical compression devices and collagen plug closure devices. Conventional
compression products are marketed by several companies that supply C-clamp
closure devices. C.R. Bard markets the Femostop compression arch, a cuff that
imposes pressure on the access site. Several new collagen-based closure devices
have been developed in response to the need for improved methods of arterial
access site closure following catheterization procedures. These collagen plug
devices are delivered through a sheath and placed at the site of the femoral
artery puncture. These collagen plugs rely on the body's clotting function,
which is enhanced by the presence of collagen, and may still require external
pressure to achieve closure of the arterial access site. In contrast, the
Company's percutaneous vascular surgery products provide a mechanical suture
closure which aids in the natural healing process and, like open surgical
repair, do not rely on the body's clotting function. Datascope and Kensey Nash
have received PMA approval from the FDA for products that use collagen plugs to
achieve hemostasis. American Home Products has exclusive worldwide distribution
rights to the Kensey Nash device. Several other companies are reported to be
developing or have tried to develop arterial closure devices, some of which have
an established presence in the field of interventional cardiology, including
Boston Scientific Corporation, C.R. Bard, Schneider (a subsidiary of Pfizer,
Inc.), United States Surgical Corporation and Guidant Corporation. In addition,
several companies are developing fibrin sealants for use as arterial access site
closure devices. The Company believes that the primary competitive factors in
the market for arterial closure devices are clinical need, complication rates,
efficacy, time to patient ambulation and discharge, ease of use and price. In
addition, the length of time required for products to be developed and to
receive regulatory and, in some cases, reimbursement approval are important
competitive factors.
 
    Competition in the market for conventional and emerging minimally invasive
CABG surgical devices is also intense and is also expected to increase. In
September 1997, United States Surgical Corporation received FDA approval to
market an anastomosis device. The Company believes that other companies,
including major interventional cardiology device companies focused on both the
conventional and minimally invasive CABG markets, are currently attempting to
develop anastomosis devices.
 
    Many of the Company's competitors have substantially greater name
recognition and financial resources than the Company and also have greater
resources and expertise in the areas of research and development, manufacturing,
marketing and regulatory affairs. There can be no assurance that the Company's
competitors will not succeed in developing and marketing technologies and
products that are more effective than those developed and marketed by the
Company or that would render the Company's technology and products obsolete or
noncompetitive. Additionally, there is no assurance that
 
                                       25
<PAGE>
the Company will be able to compete effectively against such competitors in
terms of manufacturing, marketing and sales. Also, there can be no assurance
that the Company's products will be able to demonstrate clinical efficacy or
cost effectiveness advantages over competing products, or that clinical trials
will demonstrate such advantages.
 
    In addition, the medical device market is generally characterized by rapid
and significant technological change and frequent emergence of new technologies,
products and procedures. There can be no assurance that any such new
technologies, products or procedures will not reduce the number of coronary
catheterization or CABG procedures performed. The Company's success will also
depend in part on its ability to respond quickly to medical and technological
changes through the development and introduction of new products. Product
development involves a high degree of risk and there can be no assurance that
the Company's new product development efforts will result in any commercially
successful products. The Company believes it competes favorably with respect to
these factors, although there is no assurance that it will be able to continue
to do so. See "Risk Factors -- Competition and Risk of Technological
Obsolescence."
 
PATENTS AND PROPRIETARY RIGHTS
 
    Perclose's policy is to protect its proprietary position by, among other
methods, filing United States and foreign patent applications to protect
technology, inventions and improvements that are important to its business. The
Company has three issued United States patents covering certain aspects of the
percutaneous suturing technology used in the Company's PVS products and has
exclusive licenses under two additional issued patents relating to a different
method of percutaneous suturing not currently employed by the Company's
products. The Company has seven United States patent applications pending in the
areas of device design, percutaneous suturing for vascular puncture sites and
accessory devices. The Company has also licensed, on a nonexclusive basis,
certain coating technology used in its products. Under the license, the Company
is obligated to pay royalties on sales of products using this coating
technology. The Company has filed two United States patent applications covering
its anastomosis products and intends to file additional patents in the future.
The Company has also filed several international patent applications
corresponding to certain of its United States patent applications.
 
    The patent positions of medical device companies, including those of the
Company, are uncertain and involve complex and evolving legal and factual
questions. The coverage sought in a patent application either can be denied or
significantly reduced before or after the patent is issued. Consequently, there
can be no assurance that any patent applications will result in the issuance of
patents, or that the Company's issued or any future patents will provide
significant protection or commercial advantage or will not be circumvented by
others. Since patent applications are secret until patents are issued in the
United States or corresponding applications are published in international
countries, and since publication of discoveries in the scientific or patent
literature often lags behind actual discoveries, the Company cannot be certain
that it was the first to make the inventions covered by each of its pending
patent applications or that it was the first to file patent applications for
such inventions. There can be no assurance that patents held by or licensed to
the Company or any patents that may be issued as a result of the Company's
pending or future patent applications will be of commercial benefit, afford the
Company adequate protection from competing products or technologies or will not
be challenged by competitors or others or declared invalid. Also, there can be
no assurance that the Company will have the financial resources to defend its
patents from infringement or claims of invalidity.
 
    In the event a third party has also filed a patent application relating to
an invention claimed in a Company patent application, the Company may be
required to participate in an interference proceeding declared by the USPTO to
determine priority of invention, which could result in substantial uncertainties
and costs to the Company, even if the eventual outcome is favorable to the
Company. There can be no assurance that any patents issued to the Company would
be held valid by a court of competent jurisdiction.
 
                                       26
<PAGE>
    The Company relies upon trade secret protection for certain unpatented
aspects of other proprietary technology. There is no assurance that others will
not independently develop or otherwise acquire substantially equivalent
proprietary information or techniques, others will not otherwise gain access to
the Company's proprietary technology or disclose such technology, or the Company
can meaningfully protect its trade secrets.
 
    The Company typically requires its employees and consultants to execute
appropriate confidentiality and proprietary information agreements upon the
commencement of an employment or a consulting relationship with the Company.
These agreements generally provide that all confidential information developed
or made known to the individual by the Company during the course of the
individual's relationship with the Company is to be kept confidential and not
disclosed to third parties, except in specific circumstances. The agreements
generally provide that all inventions conceived by the individual in the course
of rendering services to the Company shall be the exclusive property of the
Company; however, certain of the Company's agreements with consultants, who
typically are employed on a full-time basis by academic institutions or
hospitals, do not contain assignment of invention provisions. There can be no
assurance, however, that these agreements will provide meaningful protection or
adequate remedies for the Company in the event of unauthorized use, transfer or
disclosure of such information or inventions. See "Risk Factors -- Reliance on
Patents and Protection of Proprietary Technology."
 
GOVERNMENT REGULATION
 
    UNITED STATES REGULATION
 
    The Company's products are regulated in the United States as "medical
devices" by the FDA under the Federal Food, Drug, and Cosmetic Act ("FDC Act")
and require premarket clearance or approval by the FDA prior to
commercialization. In addition, certain material changes or modifications to
medical devices also are subject to FDA review and clearance or approval.
Pursuant to the FDC Act, the FDA regulates the research, testing, manufacture,
safety, labeling, storage, record keeping, advertising, distribution and
production of medical devices in the United States. Noncompliance with
applicable requirements can result in warning letters, fines, injunctions, civil
penalties, recall or seizure of products, total or partial suspension of
production, failure of the government to grant premarket clearance or premarket
approval for devices, and criminal prosecution. Medical devices are classified
into one of three classes, Class I, II or III, on the basis of the controls
deemed by the FDA to be necessary to reasonably ensure their safety and
effectiveness. Class I devices are subject to general controls (e.g., labeling,
premarket notification and adherence to GMPs). Class II devices are subject to
general controls and to special controls (e.g., performance standards,
postmarket surveillance, patient registries and FDA guidelines). Generally,
Class III devices are those which must receive premarket approval by the FDA to
ensure their safety and effectiveness (e.g., life-sustaining, life-supporting
and implantable devices, or new devices which have not been found substantially
equivalent to legally marketed devices), and require clinical testing to ensure
safety and effectiveness and FDA approval prior to marketing and distribution.
The FDA also has the authority to require clinical testing of Class I and Class
II devices. A PMA application must be filed if the proposed device is not
substantially equivalent to a legally marketed predicate device or if it is a
preamendment Class III device (i.e. one that has been in commercial distribution
since before May 28, 1976) for which the FDA has called for such applications.
 
    If human clinical trials of a device are required and if the device presents
a "significant risk," the manufacturer or the distributor of the device is
required to file an investigational device exemption ("IDE") application prior
to commencing human clinical trials. The IDE application must be supported by
data, typically including the results of animal and, possibly, mechanical
testing. If the IDE application is approved by the FDA, human clinical trials
may begin at a specific number of investigational sites with a maximum number of
patients, as approved by the agency. Sponsors of clinical trials are permitted
to sell those devices distributed in the course of the study provided such costs
do not exceed recovery of the
 
                                       27
<PAGE>
costs of manufacture, research, development and handling. The clinical trials
must be conducted under the auspices of an independent institutional review
board ("IRB") established pursuant to FDA regulations.
 
    Generally, before a new device can be introduced into the market in the
United States, the manufacturer or distributor must obtain FDA clearance of a
510(k) notification or approval of a PMA application. If a medical device
manufacturer or distributor can establish that a device is "substantially
equivalent" to a "predicate device" which is a legally marketed Class I or Class
II device or to a preamendment Class III device for which the FDA has not called
for PMAs, the manufacturer or distributor may seek clearance from the FDA to
market the device by submitting a 510(k) notification. The 510(k) notification
may need to be supported by appropriate data, including clinical data,
establishing the claim of substantial equivalence to the satisfaction of the
FDA. The FDA recently has been requiring a more rigorous demonstration of
substantial equivalence.
 
    Following submission of the 510(k) notification, the manufacturer or
distributor may not place the device into commercial distribution until an order
is issued by the FDA. No law or regulation specifies the time limit by which the
FDA must respond to a 510(k) notification. At this time, the Company believes
that the FDA typically responds to the submission of a 510(k) notification
within 90 to 120 days, although it can take longer. An FDA order may declare
that the device is substantially equivalent to another legally marketed device
and allow the proposed device to be marketed in the United States. The FDA,
however, may determine that the proposed device is not substantially equivalent
or require further information, including clinical data, to make a determination
regarding substantial equivalence. Such determination or request for additional
information could delay market introduction of the products that are the subject
of the 510(k) notification.
 
    If a manufacturer or distributor of medical devices cannot establish that a
proposed device is substantially equivalent to a predicate device, the
manufacturer or distributor must seek premarket approval of the proposed device
through submission of a PMA application. A PMA application must be supported by
extensive data, including preclinical and clinical trial data, as well as
extensive literature to prove the safety and effectiveness of the device.
Following receipt of a PMA application, if the FDA determines that the
application is sufficiently complete to permit a substantive review, the FDA
will "file" the application. Under the FDC Act, the FDA has 180 days to review a
PMA application, although the review of such an application more often occurs
over a protracted time period, and generally takes more than one year or more
from the date of filing to complete.
 
    The PMA application approval process can be expensive, uncertain and
lengthy. A number of devices for which premarket approval has been sought have
never been approved for marketing. The review time is often significantly
extended by the FDA, which may require more information or clarification of
information already provided in the submission. During the review period, an
advisory committee likely will be convened to review and evaluate the
application and provide recommendations to the FDA as to whether the device
should be approved. In addition, the FDA will inspect the manufacturing facility
to ensure compliance with the FDA's GMP requirements prior to approval of an
application. If granted, the approval of the PMA application may include
significant limitations on the indicated uses for which a product may be
marketed.
 
    In April 1997, the Company received PMA approval for commercial sale in the
United States of its Prostar 9F and 11F products. In November 1997, the Company
received PMA supplement approval for commercial sale in the United States of its
Techstar 6F and Techstar XL 6F products. In June 1997, the Company submitted to
the FDA a PMA supplement for the Prostar Plus 8F and 10F and Prostar XL 8F
products for sale in the United States. There can be no assurance that the
Company will be able to obtain further PMA application or PMA supplement
approvals to market its products, or any other products, on a timely basis, if
at all, and delays in receipt or failure to receive such approvals, the loss of
previously received approvals, or failure to comply with existing or future
regulatory requirements could have a material adverse effect on the Company's
business, financial condition and results of operations.
 
                                       28
<PAGE>
    In August 1997, a competitor of the Company petitioned the FDA for review of
the PMA approval granted to the Prostar 9F and 11F products. The petition was
filed pursuant to a provision of the FDC Act permitting any interested party to
request that the FDA refer an approval order and the basis for the order to an
independent advisory committee of experts, who are to review the information and
provide the FDA with a report and recommendation. Under this provision, the FDA
is required to make public the advisory committee's report and recommendation
and to issue an order either affirming, reversing or modifying the approval. To
the Company's knowledge, the FDA has conducted a review pursuant to this
provision twice since the enactment of the Medical Device Amendments of 1976.
The Company responded to the petition by submitting comments in September 1997
arguing that the FDA should deny it. No assurance can be given that the FDA will
not grant the request to convene an advisory committee to review the PMA
approval granted to the Prostar 9F and 11F products, nor can assurance be given
that the FDA will not, after such review, issue an order reversing or
unfavorably modifying the original PMA approval. Any such action by the FDA
would have a material adverse effect on the Company.
 
    The Company is also required to register as a medical device manufacturer
with the FDA and state agencies, such as the CDHS, and to list its products with
the FDA. The Company has been inspected by both the FDA and the CDHS for
compliance with the FDA's QS Reg. and other applicable regulations that require
the Company to manufacture its products according to elaborate testing, control
activities documentation and other quality assurance procedures. Further, the
Company is required to comply with various FDA requirements for design, safety,
advertising and labeling. In June 1995, the Company's Menlo Park, California
facility was inspected by the CDHS, and the Company was subsequently granted a
California medical device manufacturing license.
 
    The Company is required to provide information to the FDA on death or
serious injuries alleged to have been associated with the use of its medical
devices, as well as product malfunctions that would likely cause or contribute
to death or serious injury if the malfunction were to recur. In addition, the
FDA prohibits an approved device from being marketed for unapproved
applications. If the FDA believes that a company is not in compliance with the
law, it can institute proceedings to detain or seize products, issue a recall,
enjoin future violations and assess civil and criminal penalties against the
company, its officers and its employees. Failure to comply with the regulatory
requirements could have a material adverse effect on the Company's business,
financial condition and results of operations.
 
    The advertising of most FDA-regulated products is subject to both FDA and
Federal Trade Commission jurisdiction. The Company also is subject to regulation
by the Occupational Safety and Health Administration and by other governmental
entities.
 
    Regulations regarding the manufacture and sale of the Company's products are
subject to change. The Company cannot predict what impact, if any, such changes
might have on its business, financial condition or results of operations. See
"Risk Factors -- Government Regulation."
 
    INTERNATIONAL REGULATION
 
    International sales of the Company's products are subject to the regulatory
agency product registration requirements of each country. The regulatory review
process varies from country to country. The Company's distributors have obtained
regulatory approval in several international markets. At this time, the Prostar
8F and 10F and the Techstar 6F, 7F and 6FS products are being marketed in
Germany, France, Japan and other major countries under regulatory approvals
where required.
 
    Commercial sales of medical devices, including the Company's PVS products,
in member countries of the European Union require the manufacturer to obtain the
right to affix the CE mark, an international symbol of adherence to quality
assurance standards and compliance with applicable European medical device
directives. In July 1996, the Company received CE mark certification for its
Techstar and Prostar PVS products. In connection with CE mark certification, the
Company received ISO 9001 qualification of its manufacturing and quality
assurance processes. Certification under the ISO 9000 series of standards is one
of the CE mark certification requirements.
 
                                       29
<PAGE>
    The Company, through its Japanese distributor, has received regulatory
approval for commercial sale of its products in Japan and has commenced clinical
trials in Japan that will form the basis of an application for reimbursement
approvals in the Japanese health care system. The Company's distributor will be
responsible for management of clinical trials and obtaining reimbursement
approval for the Prostar and Techstar products in Japan. There can be no
assurance such approvals will be obtained in a timely manner or at all. See
"Risk Factors -- Government Regulation."
 
THIRD-PARTY REIMBURSEMENT
 
    In the United States, health care providers, such as hospitals and
physicians that purchase medical devices such as the Company's products,
generally rely on third-party payors, principally federal Medicare, state
Medicaid and private health insurance plans, to reimburse all or part of the
cost of therapeutic and diagnostic catheterization procedures. Reimbursement for
catheterization procedures performed using devices that have received FDA
approval has generally been available in the United States. The Company
anticipates that in a prospective payment system, such as the DRG system
utilized by Medicare, and in many managed care systems used by private health
care payors, the cost of the Company's products will be incorporated into the
overall cost of the procedure and that there will be no separate, additional
reimbursement for the Company's products. The Company anticipates that hospital
administrators and physicians will justify the additional cost of an arterial
access site closure device by the attendant cost savings and clinical benefits
derived from the use of the Company's products.
 
    Separate reimbursement for the Company's products is not expected to be
available in the United States and there can be no assurance that reimbursement
for the Company's products will be available in international markets under
either governmental or private reimbursement systems. Furthermore, the Company
could be adversely affected by changes in reimbursement policies of governmental
or private health care payors, particularly to the extent any such changes
affect reimbursement for therapeutic or diagnostic catheterization procedures in
which the Company's products are used. Failure by physicians, hospitals and
other users of the Company's products to obtain sufficient reimbursement from
health care payors for procedures in which the Company's products are used or
adverse changes in governmental and private third-party payors' policies toward
reimbursement for such procedures could have a material adverse effect on the
Company's business, financial condition and results of operations.
 
    In international markets, market acceptance of the Company's products may be
dependent in part upon the availability of reimbursement within prevailing
health care payment systems. However, in general, hospitals using the Company's
products do not receive specific, cost-based, direct reimbursement for the use
of Perclose PVS products. Reimbursement and health care payment systems in
international markets vary significantly by country. The main types of health
care payment systems in international markets are government sponsored health
care and private insurance. Countries with government sponsored health care,
such as the United Kingdom, have a centralized, nationalized health care system.
New devices are brought into the system through negotiations between departments
at individual hospitals at the time of budgeting. In most foreign countries,
there are also private insurance systems that may offer payments for alternative
therapies. Although not as prevalent as in the United States, health maintenance
organizations are emerging in certain European countries. Currently, users of
the Company's products in Germany have obtained reimbursement from certain
private payors. The Company's products have also been purchased by hospitals in
nationalized systems in the United Kingdom and Canada. The Company received
governmental reimbursement approvals for private hospitals in France that were
subsequently withdrawn in October 1996. The Company is attempting to restore its
reimbursement approvals with the French health care regulatory authorities. In
Japan, the Company is currently undertaking a clinical study to support
governmental reimbursement approvals. The Company may not receive reimbursement
approvals in Japan in a timely manner, or at all. The Company may seek
additional international reimbursement approvals, although there can be no
assurance that any such approvals will be obtained in a timely manner, or at
all, and failure to receive additional international
 
                                       30
<PAGE>
reimbursement approvals could have an adverse effect on market acceptance of the
Company's products in the international markets in which such approvals are
sought. See "Risk Factors -- Uncertainty of Third-Party Reimbursement."
 
PRODUCT LIABILITY AND INSURANCE
 
    The Company's business involves the risk of product liability claims. The
Company has not experienced any product liability claims to date. Although the
Company maintains product liability insurance, there can be no assurance that
product liability claims will not exceed such insurance coverage limits, which
could have a material adverse effect on the Company, or that such insurance will
be available on commercially reasonable terms or at all.
 
EMPLOYEES
 
    As of September 30, 1997, the Company had 136 full-time employees.
Approximately 14 persons were engaged in research and development activities, 57
persons were engaged in manufacturing and manufacturing engineering, 14 persons
were engaged in quality assurance and regulatory affairs, 39 persons were
engaged in sales and marketing and 12 persons were engaged in general and
administrative functions. No employees are covered by collective bargaining
agreements, and the Company believes it maintains good relations with its
employees. The Company is dependent upon a number of key management and
technical personnel, and the loss of services of one or more key employees could
have a material adverse effect on the Company.
 
FACILITIES
 
    The Company leases an approximately 31,000 square foot facility in Menlo
Park, California. This facility includes an environmentally controlled, Class
10,000 clean room for device assembly together with warehouse, laboratory and
office space. The facility is leased under three separate leases which expire at
various times between September 1998 and March 1999. The Company is currently
negotiating an extension of its existing leases and is evaluating relocating to
a larger facility in 1999. The Company believes it will be able to satisfy its
facilities requirements on commercially reasonable terms.
 
LEGAL PROCEEDINGS
 
    The Company is not a party to any material pending legal proceedings.
 
                                       31
<PAGE>
                                   MANAGEMENT
 
EXECUTIVE OFFICERS AND DIRECTORS
 
    The executive officers and directors of the Company and their ages as of
September 30, 1997 are as follows:
 
<TABLE>
<CAPTION>
NAME                                              AGE                                 POSITION
- --------------------------------------------      ---      --------------------------------------------------------------
<S>                                           <C>          <C>
John B. Simpson, Ph.D., M.D.(1)(5)..........          53   Chairman of the Board
Henry A. Plain, Jr.(5)......................          39   President, Chief Executive Officer and Director
Randolph E. Campbell........................          40   Vice President of Operations
Ronald W. Songer............................          40   Vice President of Research and Development
Kenneth E. Ludlum...........................          44   Vice President of Finance and Administration and Chief
                                                           Financial Officer
Coy F. Blevins..............................          49   Vice President of United States Sales
John G. McCutcheon..........................          37   Vice President of Marketing and International Sales
Vaughn D. Bryson(1)(5)......................          59   Director
Michael L. Eagle(2)(3)......................          50   Director
Serge Lashutka(3)...........................          50   Director
James W. Vetter, M.D.(4)....................          40   Director
Mark A. Wan(1)(2)(4)........................          32   Director
</TABLE>
 
- ---------
 
(1) Member of the Compensation Committee
 
(2) Member of the Audit Committee
 
(3) Class I director (defined below)
 
(4) Class II director (defined below)
 
(5) Class III director (defined below)
 
    DR. SIMPSON co-founded Perclose in March 1992 and has served as Chairman of
the Board since the Company's inception. He has served as a Staff Cardiologist
at Sequoia Hospital in Redwood City, California since 1981. Dr. Simpson is a
professor of clinical medicine at Stanford University. Dr. Simpson founded
Advanced Cardiovascular Systems, Inc. ("ACS") in 1978 and Devices for Vascular
Intervention, Inc. ("DVI") in 1984, each of which are currently divisions of
Guidant Corporation. Dr. Simpson is a director of several privately held
companies. Dr. Simpson holds a B.S. in Agriculture from Ohio State University, a
Ph.D. in Biomedical Sciences from the University of Texas at Houston and an M.D.
from Duke University.
 
    MR. PLAIN joined Perclose in February 1993 as President and Chief Executive
Officer and a member of the Company's board of directors. From 1981 until
joining the Company, Mr. Plain held various management positions in the
pharmaceutical, agricultural and medical device units of Eli Lilly and Company
("Lilly"), a diversified pharmaceutical and medical products company, including
Director of Marketing at DVI, then a subsidiary of Lilly, from 1991 to 1992. Mr.
Plain holds a B.S. in Finance from the University of Missouri.
 
    MR. BLEVINS joined Perclose as Director of U.S. Sales in January 1994 and
was promoted to Vice President, U.S. Sales in July 1996. From 1990 through 1993,
Mr. Blevins was a Regional Sales Manager with DVI. Prior to 1990, Mr. Blevins
held various sales and sales management positions at Baxter Healthcare, Inc. Mr.
Blevins holds a B.S. in Accounting from Baylor University.
 
    MR. CAMPBELL joined Perclose in January 1994 as Vice President of
Operations. From 1986 until joining the Company, Mr. Campbell held various
management positions at DVI, serving most recently as Director of Manufacturing
Engineering from 1992 to 1994 and previously as Director of Product Development
from 1990 to 1992. Mr. Campbell holds a B.S. in Chemical Engineering from the
University of California at Berkeley.
 
                                       32
<PAGE>
    MR. LUDLUM joined Perclose as Vice President of Finance and Administration
and Chief Financial Officer in May 1996. From November 1995 until joining
Perclose, Mr. Ludlum was an independent business and financial consultant to
health care and high growth companies. From November 1993 to November 1995, Mr.
Ludlum was Vice President, Finance & Administration and Chief Financial Officer
of RiboGene, Inc., a biopharmaceutical company. From December 1991 to November
1993, Mr. Ludlum was Vice President, Finance and Administration, Treasurer,
Chief Financial Officer and Secretary of Alteon Inc., a publicly traded
biopharmaceutical company developing therapies for diabetes. From 1986 to 1991,
Mr. Ludlum held various positions with Montgomery Securities in the health care
finance group. Mr. Ludlum holds a B.S. in business from Lehigh University and an
M.B.A. from Columbia Business School.
 
    MR. MCCUTCHEON joined Perclose in January 1994 as Director of Marketing. In
July 1996, Mr. McCutcheon was promoted to Vice President, Marketing and in July
1997 was promoted to Vice President of Marketing and International Sales. From
1992 until joining the Company, Mr. McCutcheon was a Marketing Manager at DVI.
From 1985 to 1992, Mr. McCutcheon held positions in sales and marketing with the
Bentley Laboratories Division of Baxter Healthcare Corporation. Mr. McCutcheon
holds a B.A. in Economics and in Psychology and an M.B.A., both from the
University of California, Los Angeles.
 
    MR. SONGER joined Perclose in April 1993 as Vice President of Research and
Development. From 1990 until joining Perclose, Mr. Songer was Director of
Catheter Systems Research and Development for the Spectranetics Corporation, a
manufacturer of laser atherectomy systems. Prior to joining Spectranetics, Mr.
Songer was Manager of Research and Development for the movable wire systems unit
of ACS. Mr. Songer holds a B.S. in Nuclear Engineering from the University of
California at Santa Barbara and an M.S. in Mechanical Engineering from the
University of California at Berkeley.
 
    MR. BRYSON has served as a Director of Perclose since January 1995. Mr.
Bryson is President of Life Science Advisors, a consulting firm focused on
assisting biopharmaceutical and medical device firms in building shareholder
value. From April 1994 to December 1996, Mr. Bryson served as Vice Chairman of
Vector Securities International, an investment bank. For 32 years, Mr. Bryson
was an employee of Lilly, where he served as Executive Vice President from 1986
until October 1991 and President and Chief Executive Officer from November 1991
to June 1993. He was a director of Lilly from 1984 until his retirement in 1993.
Mr. Bryson is a director of Ariad Pharmaceuticals, Chiron Corporation, Endo
Vascular Technologies, Fusion Medical Technologies, NaPro Bio Therapeutics and
Quintiles Transnational Corporation.
 
    MR. EAGLE has served as a Director of Perclose since September 1996. He has
held various management positions in Lilly's pharmaceutical and medical device
units since 1983 and currently serves as Vice President, Manufacturing. From
June 1993 until January 1994, he served as Vice President of pharmaceutical
manufacturing for Lilly and from January 1991 until June 1993 he served as Vice
President of the vascular intervention component of the Medical Devices and
Diagnostics Division of Lilly. From 1988 to 1991, Mr. Eagle was President and
Chief Executive Officer of IVAC Corporation, a Lilly subsidiary. From 1983 to
1988, he held various positions with ACS, a former Lilly subsidiary, serving
most recently as Senior Vice President of Manufacturing from 1985 to 1988. Mr.
Eagle holds a B.S. in Mechanical Engineering from GMI Engineering and Management
Institute and an M.S. in Industrial Administration from Purdue University.
 
    MR. LASHUTKA has served as a Director of Perclose since September 1996. He
is currently a Manager of Organizational Development of Unocal Corporation, a
major oil, gas and chemical company. From 1993 to 1996, Mr. Lashutka was
Director, Organization Development, and Senior Consultant of Pacific Health
Systems, Inc., a managed health care organization. From 1979 to 1993, he was
Manager of the Organization Effectiveness Department at the Kaiser Permanente
Medical Care Program, a major managed health care organization operating in
California. Mr. Lashutka holds a B.A. from Ohio State University, an M.A. in
Psychology from the United States International University and an M.B.A. from
the University of California at Berkeley.
 
                                       33
<PAGE>
    DR. VETTER is a co-founder of the Company and has served as a Director of
the Company and a consultant and medical advisor to the Company since its
inception. Since 1989, Dr. Vetter has served as a Staff Cardiologist at Sequoia
Hospital in Redwood City, California. Dr. Vetter holds a B.A. in Biology and
Chemistry from Augustana College and an M.D. from the University of Wisconsin.
 
    MR. WAN has served as a Director of Perclose since September 1992. He has
been a General Partner of Three Arch Partners, a venture capital firm
specializing in health care investments, since October 1993. From 1987 to 1993,
Mr. Wan held various positions at Brentwood Associates, a venture capital firm,
most recently as a General Partner. Mr. Wan has been involved in the formation
of several privately held, venture capital-backed health care companies and
serves as a director of several privately held companies. Mr. Wan holds a B.S.
in Electrical Engineering and a B.A. in Economics from Yale University and an
M.B.A. from Stanford University.
 
    Currently all directors hold office until the next annual meeting of
stockholders and until their successors have been duly elected and qualified.
The Company's board of directors has been divided into three classes. The terms
of office of the Company's Class I, Class II and Class III directors expire on
the annual meetings of stockholders in 1999, 2000, and 1998 respectively. The
board of directors has a compensation committee, which establishes compensation
policies and is responsible for determinations regarding cash and equity
compensation for executive officers, and an audit committee, which is
responsible for reviewing the scope of and work performed by the Company's
independent auditors. Officers are elected by and serve at the discretion of the
board of directors. There are no family relationships among the directors or
officers of the Company.
 
                                       34
<PAGE>
                                  UNDERWRITING
 
    Subject to the terms and conditions of the Underwriting Agreement, the
Underwriters named below (the "Underwriters"), through their Representatives, BT
Alex. Brown Incorporated and Piper Jaffray Inc., have severally agreed to
purchase from the Company the following respective number of shares of Common
Stock at the public offering price less the underwriting discounts and
commissions set forth on the cover page of this Prospectus:
 
<TABLE>
<CAPTION>
                                                                                    NUMBER OF
                                   UNDERWRITER                                       SHARES
- ---------------------------------------------------------------------------------  -----------
<S>                                                                                <C>
BT Alex. Brown Incorporated......................................................
Piper Jaffray Inc................................................................
 
                                                                                   -----------
Total............................................................................    1,000,000
                                                                                   -----------
                                                                                   -----------
</TABLE>
 
    The Underwriting Agreement provides that the obligations of the Underwriters
are subject to certain conditions precedent and that the Underwriters will
purchase all shares of the Common Stock offered hereby if any of such shares are
purchased.
 
    The Company has been advised by the Representatives of the Underwriters that
the Underwriters propose to offer the shares of Common Stock to the public at
the public offering price set forth on the cover page of this Prospectus and to
certain dealers at such price less a concession not in excess of $  per share.
The Underwriters may allow, and such dealers may reallow, a concession not in
excess of $  per share to certain other dealers. After the public offering, the
offering price and other selling terms may be changed by the Representatives.
 
    The Company has granted to the Underwriters an option, exercisable not later
than 30 days after the date of this Prospectus, to purchase up to 150,000
additional shares of Common Stock at the public offering price less the
underwriting discounts and commissions set forth on the cover page of this
Prospectus. To the extent that the Underwriters exercise such option, each of
the Underwriters will have a firm commitment to purchase approximately the same
percentage thereof that the number of shares of Common Stock to be purchased by
it shown in the above table bears to 1,000,000 and the Company will be
obligated, pursuant to the option, to sell such shares to the Underwriters. The
Underwriters may exercise such option only to cover over-allotments made in
connection with the sale of Common Stock offered hereby. If purchased, the
Underwriters will offer such additional shares on the same terms as those on
which the 1,000,000 shares are being offered.
 
    The Company has agreed to indemnify the Underwriters against certain
liabilities, including liabilities under the Securities Act of 1933, as amended.
 
    The Representatives of the Underwriters have advised the Company that the
Underwriters do not intend to confirm sales to any account over which they
exercise discretionary authority.
 
    The Company, its executive officers and directors have agreed not to offer,
sell, pledge, contract to sell, or otherwise dispose of any Common Stock for a
period of 90 days after the date of this Prospectus without the prior consent of
BT Alex. Brown Incorporated.
 
    The Underwriters have advised the Company that, as permitted by Regulation M
under the Exchange Act, certain persons participating in this offering may
engage in transactions, including stabilizing bids, syndicate covering
transactions or the imposition of penalty bids, which may have the effect of
stabilizing or maintaining the market price of the Common Stock at a level above
that which might otherwise prevail
 
                                       35
<PAGE>
in the open market. A "stabilizing bid" is a bid for or the purchase of Common
Stock on behalf of the Underwriters for the purpose of fixing or maintaining the
price of the Common Stock. A "syndicate covering transaction" is the bid for or
the purchase of the Common Stock on behalf of the Underwriters to reduce a short
position incurred by the Underwriters in connection with the offering. A
"penalty bid" is an arrangement permitting the Underwriters to reclaim the
selling concession otherwise accruing to an Underwriter or dealer in connection
with the offering if the Common Stock originally sold by such Underwriter or
dealer is purchased by the Underwriters in a syndicate covering transaction and
has therefore not been effectively placed by such Underwriter or dealer. The
Underwriters have advised the Company that such transactions may be effected on
the Nasdaq National Market or otherwise and, if commenced, may be discontinued
at any time.
 
    As permitted by Rule 103 of Regulation M under the Exchange Act,
Underwriters or prospective Underwriters that are market makers ("passive market
makers") in the Common Stock may make bids for or purchases of Common Stock on
the Nasdaq National Market until such time, if any, when a stabilizing bid for
such securities has been made. Rule 103 generally provides that: (i) a passive
market maker's net daily purchases of the Common Stock may not exceed 30% of its
average daily trading volume in such securities for the two full consecutive
calendar months (or any 60 consecutive days ending within the 10 days)
immediately preceding the filing date of the Registration Statement of which
this Prospectus forms a part, or 200 shares, whichever is greater; (ii) a
passive market maker may not effect transactions or display bids for the Common
Stock at a price that exceeds the highest independent bid for the Common Stock
by persons who are not passive market makers; and (iii) bids made by passive
market makers must be identified as such.
 
                                 LEGAL MATTERS
 
    The validity of the Common Stock offered hereby will be passed upon for the
Company by Wilson Sonsini Goodrich & Rosati, Professional Corporation, Palo
Alto, California. Certain legal matters will be passed upon for the Underwriters
by Venture Law Group, A Professional Corporation, Menlo Park, California. As of
the date of this Prospectus, members of Wilson Sonsini Goodrich & Rosati,
Professional Corporation who have represented the Company in connection with
this offering, beneficially own 3,005 shares of the Company's Common Stock. J.
Casey McGlynn is Secretary of the Company and a member of Wilson Sonsini
Goodrich & Rosati, Professional Corporation.
 
                                    EXPERTS
 
    The financial statements of Perclose, Inc. incorporated by reference in the
Company's Annual Report (Form 10-K) for the year ended March 31, 1997, have been
audited by Ernst & Young LLP, independent auditors, as set forth in their report
thereon incorporated by reference therein. Such 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.
 
                             AVAILABLE INFORMATION
 
    The Company is subject to the information requirements of 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 can be
inspected and copied at the public reference facilities maintained by the
Commission at Room 1024, 450 Fifth Street, NW, Washington, D.C. 20549, and at
the Commission's Regional Offices located at Citicorp Center, 500 West Madison
Street, Suite 1400, Chicago, Illinois 60661 and 7 World Trade Center, Suite
1300, New York, New York 10048. Copies of such material can be obtained from the
Public Reference Section of the Commission, 450 Fifth Street, NW, Washington,
D.C. 20549, at prescribed rates. The Commission maintains a World Wide Web site
that contains reports, proxy and information statements and other information
regarding registrants that file electronically with the Commission. The address
of the World Wide Web site is http://www.sec.gov.
 
                                       36
<PAGE>
    The Company has filed with the Commission a registration statement on Form
S-3 (herein, together with all amendments and exhibits, referred to as the
"Registration Statement") under the Securities Act of 1933, as amended (the
"Securities Act"), with respect to the shares of Common Stock offered hereby.
This Prospectus, which constitutes part of the Registration Statement, does not
contain all of the information set forth in the Registration Statement, certain
parts of which are omitted in accordance with the rules and regulations of the
Commission. For further information with respect to the Company and the shares
of Common Stock offered hereby, reference is made to the Registration Statement
and the exhibits and the financial statements, notes and schedules filed as a
part thereof or incorporated by reference therein, which may be inspected at the
public reference facilities of the Commission at the addresses set forth above
or through the Commission's World Wide Web site.
 
    Statements contained in this Prospectus as to the contents of any contract
or other document are not necessarily complete, and in each instance are
qualified in all respects by reference to the copy of such contract or document
filed as an exhibit to the Registration Statement.
 
                                       37
<PAGE>
- -------------------------------------------
                                     -------------------------------------------
- -------------------------------------------
                                     -------------------------------------------
 
    NO PERSON HAS BEEN AUTHORIZED IN CONNECTION WITH THE OFFERING MADE HEREBY TO
GIVE ANY INFORMATION OR TO MAKE ANY REPRESENTATION NOT CONTAINED IN THIS
PROSPECTUS AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATION MUST NOT BE
RELIED UPON AS HAVING BEEN AUTHORIZED BY THE COMPANY OR ANY UNDERWRITER. THIS
PROSPECTUS DOES NOT CONSTITUTE AN OFFER TO SELL OR A SOLICITATION OF ANY OFFER
TO BUY ANY OF THE SECURITIES OFFERED HEREBY TO ANY PERSON OR BY ANYONE IN ANY
JURISDICTION IN WHICH IT IS UNLAWFUL TO MAKE SUCH OFFER OR SOLICITATION. NEITHER
THE DELIVERY OF THIS PROSPECTUS NOR ANY SALE MADE HEREUNDER SHALL, UNDER ANY
CIRCUMSTANCES, CREATE ANY IMPLICATION THAT THE INFORMATION CONTAINED HEREIN IS
CORRECT AS OF ANY DATE SUBSEQUENT TO THE DATE HEREOF.
 
                                 --------------
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                    PAGE
                                                    -----
<S>                                              <C>
Incorporation of Certain Documents by
  Reference....................................           2
Prospectus Summary.............................           3
Risk Factors...................................           6
The Company....................................          14
Use of Proceeds................................          14
Price Range of Common Stock and Dividend
  Policy.......................................          14
Capitalization.................................          15
Selected Financial Data........................          16
Business.......................................          17
Management.....................................          32
Underwriting...................................          35
Legal Matters..................................          36
Experts........................................          36
Available Information..........................          36
</TABLE>
 
                                1,000,000 SHARES
 
                                     [LOGO]
 
                                  COMMON STOCK
 
                                  ------------
                                   PROSPECTUS
                                  ------------
 
                                 BT ALEX. BROWN
 
                               PIPER JAFFRAY INC.
 
                                          , 1997
 
- -------------------------------------------
                                     -------------------------------------------
- -------------------------------------------
                                     -------------------------------------------
<PAGE>
                                    PART II
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 13. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION
 
    The following table sets forth the costs and expenses, other than
underwriting discounts and commissions, payable by the Company in connection
with the sale of Common Stock being registered. All amounts are estimates except
the SEC registration fee and the NASD filing fee.
 
<TABLE>
<CAPTION>
<S>                                                                                                    <C>
SEC registration fee.................................................................................  $     8,189
NASD filing fee......................................................................................        3,203
Nasdaq National Market listing fee...................................................................       17,500
Printing and engraving costs.........................................................................      100,000
Legal fees and expenses..............................................................................      150,000
Accounting fees and expenses.........................................................................       50,000
Blue Sky fees and expenses...........................................................................       10,000
Transfer Agent and Registrar fees....................................................................        3,500
Miscellaneous expenses...............................................................................        7,608
                                                                                                       -----------
    Total............................................................................................  $   350,000
                                                                                                       -----------
                                                                                                       -----------
</TABLE>
 
ITEM 14. INDEMNIFICATION OF DIRECTORS AND OFFICERS
 
    Section 145 of the Delaware General Corporation Law permits a corporation to
include in its charter documents, and in agreements between the corporation and
its directors and officers, provisions expanding the scope of indemnification
beyond that specifically provided by the current law.
 
    Article VIII of the Registrant's Certificate of Incorporation provides for
the indemnification of directors to the fullest extent permissible under
Delaware law.
 
    Article VI of the Registrant's Bylaws provides for the indemnification of
officers, directors and third parties acting on behalf of the corporation if
such person acted in good faith and in a manner reasonably believed to be in and
not opposed to the best interest of the corporation, and, with respect to any
criminal action or proceeding, the indemnified party had no reason to believe
his conduct was unlawful.
 
    The Registrant has entered into indemnification agreements with its
directors and executive officers, in addition to indemnification provided for in
the Registrant's Bylaws, and intends to enter into indemnification agreements
with any new directors and executive officers in the future.
 
ITEM 15. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES
 
    (A)  EXHIBITS
 
<TABLE>
<C>          <S>                                                                       <C>
      1.1    Underwriting Agreement.
 
      3.3(1) Restated Certificate of Incorporation of the Company.
 
      3.5(1) Bylaws of the Registrant.
 
      5.1    Opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation.
 
     23.1    Consent of Ernst & Young LLP, Independent Auditors.
 
     23.2    Consent of Counsel (Included in Exhibit 5.1).
 
     24.1    Power of Attorney (see page II-3).
 
     27.1    Financial Data Schedule
</TABLE>
 
- ---------
 
(1) Exhibit incorporated by reference to like numbered exhibit to Registrant's
    Registration Statement on Form S-1 (Registration Number 33-97128).
<PAGE>
ITEM 16. UNDERTAKINGS
 
    The undersigned Registrant hereby undertakes to provide to the Underwriters
at the closing specified in the Underwriting Agreement certificates in such
denominations and registered in such names as required by the Underwriters to
permit prompt delivery to each purchaser.
 
    Insofar as indemnification by the Registrant for liabilities arising under
the Securities Act may be permitted to directors, officers and controlling
persons of the Registrant pursuant to the provisions referenced in Item 14 of
this Registration Statement or otherwise, the Registrant has been advised that
in the opinion of the Securities and Exchange Commission such indemnification is
against public policy as expressed in the Securities Act, and is, therefore,
unenforceable. In the event that a claim for indemnification against such
liabilities (other than the payment by the Registrant of expenses incurred or
paid by a director, officer, or controlling person of the Registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered hereunder, the Registrant will, unless in the opinion of its counsel
the matter has been settled by controlling precedent, submit to a court of
appropriate jurisdiction the question whether such indemnification by it is
against public policy as expressed in the Securities Act and will be governed by
the final adjudication of such issue.
 
    The undersigned Registrant hereby undertakes that:
 
    (1) For purposes of determining liability under the Securities Act of 1933,
each filing of the Registrant's annual report pursuant to section 13(a) or
section 15(d) of the Securities Exchange Act of 1934 (and, where applicable,
each filing of an employee benefit plan's annual report pursuant to section
15(d) of the Securities Exchange Act of 1934) that is incorporated by reference
in the registration statement 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.
 
    (2) To deliver or cause to be delivered with the prospectus, to each person
to whom the prospectus was 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
Securities Exchange Act of 1934; 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.
 
    (3) For purposes of determining any liability under the Securities Act, the
information omitted from the form of Prospectus filed as part of this
Registration Statement in reliance upon Rule 430A and contained in a form of
Prospectus filed by the Registrant pursuant to Rule 424(b)(1) or (4) or 497(h)
under the Securities Act shall be deemed to be part of this Registration
Statement as of the time it was declared effective.
 
    (4) For the purpose of determining any liability under the Securities Act,
each post-effective amendment that contains a form of Prospectus shall be deemed
to be a new registration statement relating to the securities offered therein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof.
 
                                      II-2
<PAGE>
                                   SIGNATURES
 
    Pursuant to the requirements of the Securities Act, the Registrant has duly
caused this Registration Statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of Menlo Park, State of
California, on the 5th day of November, 1997.
 
<TABLE>
<S>                             <C>  <C>
                                PERCLOSE, INC.
 
                                By:           /s/ HENRY A. PLAIN, JR.
                                     -----------------------------------------
                                                Henry A. Plain, Jr.,
                                       PRESIDENT AND CHIEF EXECUTIVE OFFICER
</TABLE>
 
POWER OF ATTORNEY
 
    KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints Henry A. Plain, Jr. and Kenneth E. Ludlum and
each of them, his attorneys-in-fact, each with the power of substitution, for
him and in his name, place and stead, in any and all capacities, to sign any and
all amendments (including post-effective amendments) to this Registration
Statement, and to sign any registration statement for the same offering covered
by this Registration Statement that is to be effective upon filing pursuant to
Rule 462(b) promulgated under the Securities Act of 1933, and all post-effective
amendments thereto, and to file the same, with all exhibits thereto in all
documents in connection therewith, with the Securities and Exchange Commission,
granting unto said attorneys-in-fact and agents, and each of them, full power
and authority to do and perform each and every act and thing requisite and
necessary to be done in and about the premises, as fully to all intents and
purposes as he might or could do in person, hereby ratifying and confirming all
that such attorneys-in-fact and agents or any of them, or his or their
substitute or substitutes, may lawfully 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:
 
<TABLE>
<CAPTION>
          SIGNATURE                       TITLE                    DATE
- ------------------------------  --------------------------  -------------------
 
<C>                             <S>                         <C>
                                President, Chief Executive
   /s/ HENRY A. PLAIN, JR.        Officer and Director
- ------------------------------    (Principal Executive       November 5, 1997
     Henry A. Plain, Jr.          Officer)
 
                                Vice President and Chief
    /s/ KENNETH E. LUDLUM         Financial Officer
- ------------------------------    (Principal Financial and   November 5, 1997
      Kenneth E. Ludlum           Accounting Officer)
 
     /s/ VAUGHN D. BRYSON
- ------------------------------  Director                     November 5, 1997
       Vaughn D. Bryson
 
     /s/ MICHAEL L. EAGLE
- ------------------------------  Director                     November 5, 1997
       Michael L. Eagle
</TABLE>
 
                                      II-3
<PAGE>
<TABLE>
<CAPTION>
          SIGNATURE                       TITLE                    DATE
- ------------------------------  --------------------------  -------------------
 
<C>                             <S>                         <C>
      /s/ SERGE LASHUTKA
- ------------------------------  Director                     November 5, 1997
        Serge Lashutka
 
 /s/ JOHN B. SIMPSON, PH.D.,
             M.D.
- ------------------------------  Director                     November 5, 1997
 John B. Simpson, Ph.D., M.D.
 
  /s/ JAMES W. VETTER, M.D.
- ------------------------------  Director                     November 5, 1997
    James W. Vetter, M.D.
 
       /s/ MARK A. WAN
- ------------------------------  Director                     November 5, 1997
         Mark A. Wan
</TABLE>
 
                                      II-4
<PAGE>
                                 EXHIBIT INDEX
 
<TABLE>
<CAPTION>
 EXHIBITS
- -----------
<C>          <S>
      1.1    Underwriting Agreement.
      3.3(1) Restated Certificate of Incorporation of the Company
      3.5(1) Bylaws of the Registrant
      5.1    Opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation.
     23.1    Consent of Ernst & Young LLP, Independent Auditors.
     23.2    Consent of Counsel included in Exhibit 5.1.
     24.1    Power of Attorney (See page II-3).
     27.1    Financial Data Schedule
</TABLE>
 
- ---------
 
(1) Exhibit incorporated by reference to like numbered exhibit to Registrant's
    Registration Statement on Form S-1 (Registration Number 33-97128).

<PAGE>
                                1,000,000 SHARES
                                 PERCLOSE, INC.
                                  COMMON STOCK
                               ($0.001 PAR VALUE)
                             UNDERWRITING AGREEMENT
 
                                                               November   , 1997
 
BT ALEX. BROWN INCORPORATED
PIPER JAFFRAY INC.
As Representatives of the Several Underwriters
c/o BT Alex. Brown Incorporated
One South Street
Baltimore, Maryland 21202
 
Ladies and Gentlemen:
 
    Perclose, Inc., a Delaware corporation (the "Company"), proposes to sell to
the several underwriters (the "Underwriters") named in Schedule I hereto for
whom you are acting as representatives (the "Representatives") an aggregate of
1,000,000 shares of the Company's Common Stock, $0.001 par value (the "Firm
Shares"). The respective amounts of the Firm Shares to be so purchased by the
several Underwriters are set forth opposite their names in Schedule I hereto.
The Company also proposes to sell at the Underwriters' option an aggregate of up
to 150,000 additional shares of the Company's Common Stock (the "Option Shares")
as set forth below. If the firms listed in Schedule I hereto include only the
Representatives, then the terms, "Underwriters" and "Representatives," as used
herein, shall each be deemed to refer to such firms.
 
    As Representatives, you have advised the Company (a) that you are authorized
to enter into this Agreement on behalf of the several Underwriters, and (b) that
the several Underwriters are willing, acting severally and not jointly, to
purchase the numbers of Firm Shares set forth opposite their respective names in
Schedule I, plus their pro rata portion of the Option Shares if you elect to
exercise the over-allotment option in whole or in part for the accounts of the
several Underwriters. The Firm Shares and the Option Shares (to the extent the
aforementioned option is exercised) are herein collectively called the "Shares."
 
    In consideration of the mutual agreements contained herein and of the
interests of the parties in the transactions contemplated hereby, the parties
hereto agree as follows:
 
    1.  REPRESENTATIONS AND WARRANTIES OF THE COMPANY.
 
        (a) The Company represents and warrants as follows:
 
            (i) A registration statement on Form S-3 (File No. 333-     ) with
       respect to the Shares has been carefully prepared by the Company in
       conformity with the requirements of the Securities Act of 1933, as
       amended (the "Act"), and the Rules and Regulations (the "Rules and
       Regulations") of the Securities and Exchange Commission (the
       "Commission") thereunder and has been filed with the Commission under the
       Act. The Incorporated Documents (as defined) heretofore filed, when they
       were filed (or, if any amendment with respect to any such document was
       filed, when such amendment was filed), conformed in all material respects
       with the requirements of the Exchange Act (as defined) and the rules and
       regulations of the Commission thereunder. The Company has complied with
       the conditions for the use of Form S-3. Copies of such registration
       statement, including any amendments thereto, the preliminary prospectuses
       (meeting the requirements of Rule 430A of the Rules and Regulations)
       contained therein and the exhibits, financial statements and schedules,
       as finally amended and revised through the
<PAGE>
       date hereof, have heretofore been delivered by the Company to you. The
       term "Registration Statement" as used in this Agreement shall mean the
       registration statement and the prospectus, including all financial
       statements, schedules and exhibits, included or incorporated by reference
       therein (the "Incorporated Documents") that the Company has filed with
       the Securities Exchange Act of 1934 ("Exchange Act") the form in which it
       became or becomes, as the case may be, effective (including, if the
       Company omitted information from the registration statement pursuant to
       Rule 430A of the Rules and Regulations, the information deemed to be a
       part of the registration statement at the time it became effective
       pursuant to Rule 430A of the Rules and Regulations) and, in any a term
       sheet used pursuant to Rule 434, and in the event of any amendment
       thereto after the effective date of such registration statement, shall
       also mean (from and after the effectiveness of such amendment) such
       registration statement as so amended. If the Company has filed an
       abbreviated registration statement to register additional shares of
       Common Stock pursuant to Rule 462(b) under the Securities Act (the "Rule
       462 Registration Statement"), then any reference herein to the term
       "Registration Statement" shall also be deemed to include such Rule 462
       Registration Statement. The Registration Statement has been declared
       effective by the Commission under the Act, and no post-effective
       amendment to the Registration Statement has been filed as of the date of
       this Agreement. The form of prospectus filed by the Company with the
       Commission pursuant to its Rule 424(b) and Rule 430A is herein referred
       to as the "Prospectus." Each preliminary prospectus included in the
       Registration Statement prior to the time it becomes effective is herein
       referred to as a "Preliminary Prospectus."
 
            (ii) The Company has been duly organized and is validly existing as
       a corporation in good standing under the laws of the State of Delaware,
       with corporate power and authority to own its properties and conduct its
       business as described in the Registration Statement; and is duly
       qualified to transact business in all jurisdictions in which the conduct
       of its business requires such qualification and in which the failure so
       to qualify would materially adversely affect the business, condition
       (financial or otherwise) results of operations or prospects for the
       future of the Company. The Company has no subsidiaries.
 
           (iii) The Company has authorized and outstanding capital stock as set
       forth under the heading "Capitalization" in the Prospectus and such
       capital stock conforms in all material respects to the statements
       relating thereto contained in the Registration Statement and the
       Prospectus and any Incorporated Document (and such statements correctly
       state the substance of the instruments defining the capitalization of the
       Company; the outstanding shares of Common Stock of the Company, have been
       duly authorized and validly issued, are fully paid and non-assessable and
       have been issued in compliance with all applicable federal and state
       securities laws; the shares of Common Stock to be sold by the Company
       have been duly authorized and, when issued hereunder, will be validly
       issued, fully paid and non-assessable and will have been issued in
       compliance with all federal and state securities laws; no shareholder of
       the Company has any right pursuant to any agreement which has not been
       waived to require the Company to register the sale of any shares owned by
       such shareholder under the Act in the public offering contemplated
       hereby; all necessary and proper corporate proceedings have been taken in
       order validly to authorize and issue such authorized Common Stock and no
       further approval or authority of the shareholders or the Board of
       Directors of the Company is required for the sale of the Shares to be
       sold by the Company as contemplated hereby.
 
           (iv) The Shares conform with the statements concerning them in the
       Registration Statement in all material respects. Except as specifically
       disclosed in the Registration Statement and the financial statements of
       the Company and the related notes thereto, the Company does not have
       outstanding any options to purchase, or any preemptive rights or other
       rights to subscribe for or to purchase, any securities or obligations
       convertible into, or any contacts or commitments to issue or sell shares
       of its capital stock or any such options, rights, convertible securities
       or obligations. The descriptions of the Company's stock option, stock
       purchase and other stock-
 
                                       2
<PAGE>
       based plans, and of the options or other rights granted and exercised
       thereunder, set forth in the Prospectus or incorporated therein, are
       accurate summaries and fairly present the information required to be
       shown with respect to such plans and rights in all material respects.
 
            (v) The Commission has not issued any order preventing or suspending
       the use of any Preliminary Prospectus or instituted proceedings for that
       purpose, and each such Preliminary Prospectus has conformed in all
       material respects to the requirements of the Act and the Rules and
       Regulations and, as of its date, has not included any untrue statement of
       a material fact or omitted to state a material fact necessary to make the
       statements therein, in the light of the circumstances under which they
       were made, not misleading; and at the time the Registration Statement
       became or becomes, as the case may be, effective and at all times
       subsequent thereto up to and on the Closing Date (hereinafter defined)
       and on any later date on which Option Shares are to be purchased, (A) the
       Registration Statement and the Prospectus, and any amendments or
       supplements thereto, contained and will contain all material information
       required to be included therein by the Act and the Rules and Regulations
       and will in all material respects conform to the requirements of the Act
       and the Rules and Regulations, (B) the Registration Statement, and any
       amendments or supplements thereto, did not and will not include any
       untrue statement of a material fact or omit to state a material fact
       required to be stated therein or necessary to make the statements therein
       not misleading, and (C) the Prospectus, and any amendments or supplements
       thereto, did not and will not include any untrue statement of a material
       fact or omit to state a material fact necessary to make the statements
       therein, in the light of the circumstances under which they were made,
       not misleading; PROVIDED, HOWEVER, that none of the representations and
       warranties contained in this subparagraph (v) shall apply to information
       contained in or omitted from the Registration Statement or Prospectus, or
       any amendment or supplement thereto, in reliance upon, and in conformity
       with, written information relating to any Underwriter furnished to the
       Company by such Underwriter specifically for use in the preparation
       thereof. No Incorporated Document when it was filed (or, if an
       amendment), amendment with respect to any such document was filed, when
       such amendment was filed), contained any untrue statement of a material
       fact or omitted to state a material fact required to be stated therein or
       necessary to make the statements therein not misleading; and no such
       further amendment will contain any untrue statement of a material fact or
       omit to state a material fact required to be stated therein or necessary
       to make the statements therein not misleading.
 
           (vi) The financial statements of the Company, together with related
       notes and schedules as set forth in the Registration Statement, present
       fairly the financial position and results of operations of the Company,
       at the indicated dates and for the indicated periods. Such financial
       statements, schedules and related notes have been prepared in accordance
       with generally accepted accounting principles, consistently applied
       throughout the periods involved, and all adjustments necessary for a fair
       presentation of results for such periods have been made. The summary
       financial and statistical data and schedules included in the Registration
       Statement present fairly the information shown therein and have been
       compiled on a basis consistent with the financial statements presented
       therein. No other financial statements or schedules are required to be
       included in the Registration Statement.
 
           (vii) There is no material action, suit or proceeding pending or, to
       the knowledge of the Company, after due inquiry, threatened against the
       Company before any court or regulatory, governmental or administrative
       agency or body which might result in any material adverse change in the
       business or condition (financial or otherwise) or results of operation or
       prospects for the future of the Company except as set forth in the
       Registration Statement. The Company is not a party or subject to the
       provisions of any injunction, judgment, order, decree or of any court, or
       any regulatory, administrative or governmental body or agency.
 
          (viii) The Company has good and marketable title to all of the
       properties and assets owned by the Company reflected in either the
       financial statements or as described in the Registration
 
                                       3
<PAGE>
       Statement and is subject to no lien, mortgage, security interest, pledge
       or encumbrance of any kind, except those reflected in such financial
       statements or as described in the Registration Statement and except for
       such encumbrances that, individually or in the aggregate, would not have
       a material adverse effect on the Company. The Company occupies its leased
       properties under valid and binding leases conforming to the description
       thereof set forth in the Registration Statement.
 
           (ix) The Company has filed all foreign, federal, state and local
       income tax returns which have been required to be filed and has paid all
       taxes indicated by said returns and all assessments received by it. There
       is no tax deficiency which has been or might reasonably be expected to be
       asserted or threatened against the Company which could materially
       adversely affect the business, operations or property of the Company. The
       Company has paid all sales, user and transfer taxes applicable to it and
       its business and operations which were or are due. The Company has not
       received any notice or deficiency or claim for payment from any
       governmental or regulatory body with respect to such sales, user or
       transfer taxes.
 
            (x) Since the respective dates as of which information is given in
       the Registration Statement and Prospectus, as it may be amended or
       supplemented, (A) there has not been any material adverse change or
       development involving a prospective material adverse change in or
       affecting the business management, condition (financial or otherwise),
       results of operations or prospects for the future of the Company whether
       or not occurring in the ordinary course of business, (B) there has not
       been any transaction entered into by the Company, other than transactions
       in the ordinary course or transactions specifically described in the
       Registration Statement, as it may be amended or supplemented, (C) the
       Company has not sustained any material loss or interference with its
       businesses or properties from fire, flood, windstorm, accident or other
       calamity, not covered by insurance, (D) the Company has not paid or
       declared any dividends or other distribution with respect to its capital
       stock, except as described in the Registration Statement, and the Company
       is not in default in the payment of principal of or interest on any
       outstanding debt obligations and (E) there has not been any change in the
       capital stock (other than the sale of the Shares, the conversion of the
       Preferred Stock into Common Stock or the exercise of outstanding stock
       options pursuant to the Company's stock option plan described in the
       Registration Statement) or material increase in indebtedness of the
       Company. The Company does not have any material contingent obligation
       which is not disclosed in the Registration Statement (or contained in the
       financial statements or related notes thereto), as such may be amended or
       supplemented.
 
           (xi) The Company is not in violation or default under any provision
       of its Certificate of Incorporation or bylaws, or any of its agreements,
       leases, licenses, contracts, franchises, mortgages, permits, deeds of
       trust, indentures or other instruments or obligations to which the
       Company is a party or by which it or any of its properties is or may be
       bound or affected, except where such violation or default would not have
       a material adverse effect on the business, condition (financial or
       otherwise) or results of operations of the Company.
 
           (xii) The execution, delivery and performance of this Agreement and
       the consummation of the transactions herein contemplated do not and will
       not conflict with or result in a breach of, or violation of, any of the
       terms or provisions of, or constitute, either by itself or the giving of
       notice or the passage of time or both, a default under, any indenture,
       license, mortgage, lease, franchise, permit, deed of trust or other
       agreement or instrument to which the Company is a party or by which the
       Company or any of its property is or may be bound or affected, except
       where such breach, violation or default would not have a material adverse
       effect on the business, condition (financial or otherwise) or results of
       operations of the Company, or violate any of the provisions of the
       Certificate of Incorporation or bylaws of the Company or violate any
       injunction, judgment, order, decree, statute, rule or regulation
       applicable to the Company of any court or of any regulatory,
       administrative or governmental body or agency having jurisdiction over
       the Company or any of its property.
 
                                       4
<PAGE>
          (xiii) The Company has the legal right, corporate power and authority
       to enter into this Agreement and perform the transactions contemplated
       hereby. This Agreement has been duly authorized, executed and delivered
       by the Company.
 
          (xiv) Each approval, registration, qualification, license, permit,
       consent, order, authorization, designation, declaration or filing by or
       with any regulatory, administrative or other governmental body or agency
       necessary in connection with the execution and delivery by the Company of
       this Agreement and the consummation of the transactions herein
       contemplated (except such additional steps as may be required by the
       National Association of Securities Dealers, Inc. (the "NASD") or may be
       necessary to qualify the Shares for public offering by the Underwriters
       under state securities or Blue Sky laws) has been obtained or made and
       each is in full force and effect.
 
           (xv) Except as otherwise expressly described in the Registration
       Statement, the Company owns or possesses adequate and sufficient rights
       to use all patents, patent rights, trade secrets, licenses or royalty
       arrangements, trademarks and trademark rights, service marks, trade
       names, copyrights, know how or proprietary techniques or rights thereto
       of others, and governmental, regulatory or administrative authorizations,
       order, permits certificates and consents necessary for the conduct of the
       business of the Company, except where the failure to possess such would
       not have a material adverse effect on the business, condition (financial
       or otherwise) or results of operations of the Company; the Company is not
       aware of any material pending or threatened action, suit, proceeding or
       claim by others, either domestically or internationally, that the Company
       is violating any patents, patent rights, copyrights, trademarks or
       trademark rights, inventions, service marks, tradenames, licenses or
       royalty arrangements, trade secrets, know how or proprietary techniques
       or rights thereto of others, or governmental, regulatory or
       administrative authorizations, orders, permits, certificates and
       consents; except as otherwise expressly described in the Registration
       Statement, the Company is not aware of any rights of third parties to, or
       any infringement of, any of the Company's trademarks or trademark rights,
       copyrights, licenses or royalty arrangements, trade secrets, know how or
       proprietary techniques, including processes and substances, or rights
       thereto of others, which could materially adversely affect the use
       thereof by the Company; the Company is not aware of any pending or
       threatened material action, suit, proceeding or claim by others
       challenging the validity or scope of any of such trademarks or trademark
       rights, copyrights, licenses or royalty arrangements, trade secrets, know
       how, or proprietary techniques or rights thereto of others.
 
          (xvi) There are no contracts or other documents required to be
       described in the Registration Statement or to be filed as exhibits to or
       incorporated by reference the Registration Statement by the Act or by the
       Rules and Regulations or the Exchange Act which have not been described
       or filed as required.
 
          (xvii) The Company is conducting business in compliance with all
       applicable laws, rules and regulations, of the jurisdictions in which it
       is conducting business including, without limitation, all applicable
       local, state, federal and foreign medical devise and environmental laws
       and regulations, except where the failure to so comply would not have a
       material adverse effect on the business, condition (financial or
       otherwise) or results of operations of the Company.
 
         (xviii) The Company has not, directly or indirectly, at any time during
       the past five years (A) made any unlawful contribution to any candidate
       for public office, or failed to disclose fully any contribution in
       violation of laws, or (B) made any payment to any federal, state or local
       governmental officer or official, or other person charged with similar
       public or quasi-public duties, other than payments required or permitted
       by the laws of the United States of any jurisdiction thereof.
 
          (xix) The Company maintains insurance of the types and in the amounts
       which it deems adequate for its business, including, but not limited to,
       general liability insurance and insurance
 
                                       5
<PAGE>
       governing all real and personal property owned or leased by the Company
       against theft, damage, destruction, acts of vandalism and all other risk
       customarily insured against, all of which insurance is in full force and
       effect.
 
           (xx) Ernst & Young, LLP, who have certified the financial statements
       filed with the Commission as part of the Registration Statement, are
       independent public accountants as required by the Act and the Rules and
       Regulations.
 
          (xxi) No offering, sales or other disposition of any Common Stock of
       the Company will be made for a period of 90 days after the date of this
       Agreement, directly or indirectly, by the Company, otherwise than
       hereunder or with the prior written consent of the Representatives or
       pursuant to the grant by the Company of stock options or stock purchase
       rights or the exercise of outstanding stock options or stock purchase
       rights under the Company's Incentive Stock Plans described in the
       Registration Statement.
 
          (xxii) The Common Stock is registered pursuant to Section 12(g) of the
       Exchange Act and is listed on the Nasdaq National Market, and the Company
       has taken no action designed to, or likely to have the effect of,
       terminating the registration of the Common Stock under the Exchange Act
       or delisting the Common Stock from the Nasdaq National Market, nor has
       the Company received any notification that the Commission or the National
       Association of Securities Dealers, Inc. ("NASD") is contemplating
       terminating such registration or listing.
 
         (xxiii) The Company has been advised concerning the Investment Company
       Act of 1940, as amended (the "1940 Act"), and the rules and regulations
       thereunder, and has in the past conducted, and intends in the future to
       conduct, its affairs in such a manner as to ensure that it will not
       become an "investment company" or a company "controlled" by an
       "investment company" within the meaning of the 1940 Act and such rules
       and regulations.
 
         (xxiv) The Company has not distributed and will not distribute prior to
       the later of (i) the Closing Date, or any date on which Option Shares are
       to be purchased, as the case may be, and (ii) completion of the
       distribution of the Shares, any offering material in connection with the
       offering and sale of the Shares other than any Preliminary Prospectuses,
       the Prospectus, the Registration Statement and other materials, if any,
       permitted by the Act.
 
           (xv) The Company has not taken and will not take, directly or
       indirectly, any action designed to or that might reasonably be expected
       to cause or result in stabilization or manipulation of the price of the
       Common Stock to facilitate the sale or resale of the Shares.
 
    2.  PURCHASE, SALE AND DELIVERY OF THE FIRM SHARES.  On the basis of the
representations, warranties and covenants herein contained, and subject to the
conditions herein set forth, the Company agrees to sell to the Underwriters, and
each Underwriter agrees, severally and not jointly, to purchase, at a price of
$        per share, the number of Firm Shares set forth opposite the name of
each Underwriter in Schedule I hereof, subject to adjustments in accordance with
Section 9 hereof.
 
    Payment for the Firm Shares to be sold hereunder is to be made in same day
federal funds against delivery of certificates therefor to the Representatives
for the several accounts of the Underwriters. Such payment and delivery are to
be made at the offices of BT Alex. Brown Incorporated, One South Street,
Baltimore, Maryland 21202 at 10:00 a.m. Baltimore time, on the third business
day after the date of this Agreement or at such other time and date not later
than three business days thereafter as you and the Company shall agree upon in
writing, such time and date being herein referred to as the "Closing Date." (As
used herein, "business day" means a day on which the New York Stock Exchange is
open for trading and on which banks in New York are open for business and are
not permitted by law or executive order to be closed.) The certificates for the
Firm Shares will be delivered in such denominations and in such registrations as
the Representatives request in writing not later than the third business day
prior to the Closing Date, and will be made available for inspection by the
Representatives at least one business day prior to the Closing Date.
 
                                       6
<PAGE>
    In addition, on the basis of the representations and warranties herein
contained and subject to the terms and conditions herein set forth, the Company
hereby grants an option to the several Underwriters to purchase the Option
Shares at the price per share as set forth in the first paragraph of this
Section 2. The option granted hereby may be exercised in whole or in part but
only once and at any time upon written notice given within 30 days after the
date of this Agreement, by you, as Representatives of the several Underwriters,
to the Company setting forth the number of Option Shares as to which the several
Underwriters are exercising the option, the names and denominations in which the
Option Shares are to be registered and the time and date at which such
certificates are to be delivered. The time and date at which certificates for
Option Shares are to be delivered shall be determined by the Representatives but
shall not be earlier than three nor later than 10 full business days after the
exercise of such option, nor in any event prior to the Closing Date (such time
and date being herein referred to as the "Option Closing Date"). If the date of
exercise of the option is three or more days before the Closing Date, the notice
of exercise shall set the Closing Date as the Option Closing Date. The number of
Option Shares to be purchased by each Underwriter shall be in the same
proportion to the total number of Option Shares being purchased as the number of
Firm Shares being purchased by such Underwriter bears to 1,000,000, adjusted by
you in such manner as to avoid fractional shares. The option with respect to the
Option Shares granted hereunder may be exercised only to cover over-allotments
in the sale of the Firm Shares by the Underwriters. You, as Representatives of
the several Underwriters, may cancel such option at any time prior to its
expiration by giving written notice of such cancellation to the Company. To the
extent, if any, that the option is exercised, payment for the Option Shares
shall be made on the Option Closing Date in same day federal funds against
delivery of certificates therefor at the offices of BT Alex. Brown Incorporated,
One South Street, Baltimore, Maryland 21202.
 
    3.  OFFERING BY THE UNDERWRITERS.  It is understood that the several
Underwriters are to make a public offering of the Firm Shares as soon as the
Representatives deem it advisable to do so. The Firm Shares are to be offered to
the public at the initial public offering price set forth in the Prospectus. The
Representatives may from time to time thereafter change the public offering
price and other selling terms. To the extent, if at all, that any Option Shares
are purchased pursuant to Section 2 hereof, the Underwriters will offer them to
the public on the foregoing terms.
 
    It is further understood that you will act as the Representatives for the
Underwriters in the offering and sale of the Shares in accordance with a Master
Agreement Among Underwriters entered into by you and the several other
Underwriters.
 
    4.  COVENANTS OF THE COMPANY.
 
        (a) The Company covenants and agrees with the several Underwriters that:
 
            (i) The Company will use its best efforts to cause the Registration
       Statement and any amendment thereof, if not effective at the time and
       date that this Agreement is executed and delivered by the parties hereto,
       to become effective as promptly as possible; the Company will use its
       best efforts to cause any abbreviated registration statement pursuant to
       Rule 462(b) of the Rules and Regulations as may be required subsequent to
       the date the Registration Statement is declared effective to become
       effective as promptly as possible; the Company will notify you, promptly
       after it shall receive notice thereof, of the time when the Registration
       Statement, any subsequent amendment to the Registration Statement or any
       abbreviated registration statement has become effective or any supplement
       to the Prospectus has been filed; if the Company omitted information from
       the Registration Statement at the time it was originally declared
       effective in reliance upon Rule 430A(a) of the Rules and Regulations, the
       Company will provide evidence satisfactory to you that the Prospectus
       contains such information and has been filed, within the time period
       prescribed, with the Commission pursuant to subparagraph (1) or (4) of
       Rule 424(b) of the Rules and Regulations or as part of a post-effective
       amendment to such Registration Statement as originally declared effective
       which is declared effective by the Commission; if the Company files a
       term sheet pursuant to Rule 434 of the Rules and Regulations, the Company
       will provide evidence satisfactory to you that the Prospectus and term
       sheet
 
                                       7
<PAGE>
       meeting the requirements of Rule 434(b) or (c), as applicable, of the
       Rules and Regulations, have been filed, within the time period
       prescribed, with the Commission pursuant to subparagraph (7) of Rule
       424(b) of the Rules and Regulations; if for any reason the filing of the
       final form of Prospectus is required under Rule 424(b)(3) of the Rules
       and Regulations, it will provide evidence satisfactory to you that the
       Prospectus contains such information and has been filed with the
       Commission within the time period prescribed; it will notify you promptly
       of any request by the Commission for the amending or supplementing of the
       Registration Statement or the Prospectus or for additional information;
       promptly upon your request, it will prepare and file with the Commission
       any amendments or supplements to the Registration Statement or Prospectus
       which, in the opinion of counsel for the several Underwriters
       ("Underwriters' Counsel"), may be necessary or advisable in connection
       with the distribution of the Shares by the Underwriters; it will promptly
       prepare and file with the Commission, and promptly notify you of the
       filing of, any amendments or supplements to the Registration Statement or
       Prospectus which may be necessary to correct any statements or omissions,
       if, at any time when a prospectus relating to the Shares is required to
       be delivered under the Act, any event shall have occurred as a result of
       which the Prospectus or any other prospectus relating to the Shares as
       then in effect would include any untrue statement of a material fact or
       omit to state a material fact necessary to make the statements therein,
       in the light of the circumstances under which they were made, not
       misleading; in case any Underwriter is required to deliver a prospectus
       nine (9) months or more after the effective date of the Registration
       Statement in connection with the sale of the Shares, it will prepare
       promptly upon request, but at the expense of such Underwriter, such
       amendment or amendments to the Registration Statement and such prospectus
       or prospectuses as may be necessary to permit compliance with the
       requirements of Section 10(a)(3) of the Act; and it will file no
       amendment or supplement to the Registration Statement or Prospectus or
       the Incorporated Documents, or, prior to the end of the period of time in
       which a prospectus relating to the Shares is required to be delivered
       under the Act, file any document which upon filing becomes an
       Incorporated Document, which shall not previously have been submitted to
       you a reasonable time prior to the proposed filing thereof or to which
       you shall reasonably object in writing, subject, however, to compliance
       with the Act and the Rules and Regulations , the Exchange Act and the
       rules and regulations of the Commission thereunder and the provisions of
       this Agreement.
 
            (ii) The Company will advise the Representatives promptly of any
       request of the Commission for amendment of the Registration Statement or
       for supplement to the Prospectus or for any additional information, or of
       the issuance by the Commission of any stop order suspending the
       effectiveness of the Registration Statement or the use of the Prospectus
       or of the institution of any proceedings for that purpose, and the
       Company will use its best efforts to prevent the issuance of any such
       stop order preventing or suspending the use of the Prospectus and to
       obtain as soon as possible the lifting thereof, if issued.
 
           (iii) The Company will cooperate with the Representatives in
       endeavoring to qualify the Shares for sale under the securities laws of
       such jurisdictions as the Representatives may reasonably have designated
       in writing and will make such applications, file such documents, and
       furnish such information as may be reasonably required for that purpose,
       provided the Company shall not be required to qualify as a foreign
       corporation or to file a general consent to service of process in any
       jurisdiction where it is not now so qualified or required to file such a
       consent. The Company will, from time to time, prepare and file such
       statements, reports, and other documents, as are or may be required to
       continue such qualifications in effect for so long a period as the
       Representatives may reasonably request for distribution of the Shares.
 
           (iv) The Company will furnish to you, as soon as available, and, in
       the case of the Prospectus and any term sheet or abbreviated term sheet
       under Rule 434, in no event later than the first (1st) full business day
       following the first day that Shares are traded, copies of the
       Registration Statement (three of which will be signed and which will
       include all exhibits), each Preliminary
 
                                       8
<PAGE>
       Prospectus, the Prospectus and any amendments or supplements to such
       documents, including any prospectus prepared to permit compliance with
       Section 10(a)(3) of the Act, and the Incorporated Documents (three of
       which will include all exhibits,) all in such quantities as you may from
       time to time reasonably request. Notwithstanding the foregoing, BT Alex.
       Brown Incorporated, on behalf of the several Underwriters, shall agree to
       the utilization of Rule 434 of the Rules and Regulations, the Company
       shall provide to you copies of a Preliminary Prospectus updated in all
       respects through the date specified by you in such quantities as you may
       from time to time reasonably request.
 
            (v) If during the period in which a prospectus is required by law to
       be delivered by an Underwriter or dealer any event shall occur as a
       result of which, in the judgment of the Company or in the reasonable
       opinion of counsel for the Underwriters, it becomes necessary to amend or
       supplement the Prospectus in order to make the statements therein, in the
       light of the circumstances existing at the time the Prospectus is
       delivered to a purchaser, not misleading, or, if it is necessary at any
       time to amend or supplement the Prospectus to comply with any law, the
       Company promptly will prepare and file with the Commission an appropriate
       amendment to the Registration Statement or supplement to the Prospectus
       so that the Prospectus as so amended or supplemented will not, in the
       light of the circumstances when it is so delivered, be misleading, or so
       that the Prospectus will comply with the law.
 
           (vi) [The Company will make generally available to its security
       holders, as soon as it is practicable to do so, but in any event not
       later than 15 months after the effective date of the Registration
       Statement, an earnings statement (which need not be audited) in
       reasonable detail, covering a period of at least 12 consecutive months
       beginning after the effective date of the Registration Statement, which
       earnings statement shall satisfy the requirements of Section 11(a) of the
       Act and Rule 158 of the Rules and Regulations and will advise you in
       writing when such statement has been so made available.]
 
           (vii) No offering, sale or other disposition of any Common Stock of
       the Company will be made for a period of 90 days after the date of this
       Agreement, directly or indirectly, by the Company otherwise than
       hereunder or with the prior written consent of the Representatives except
       that the Company may, without such consent, issue shares (A) upon the
       exercise of options outstanding on the date of this Agreement issued
       pursuant to the Company's 1992 Stock Plan or 1995 Director Option Plan or
       pursuant to the Company's 1995 Employee Stock Purchase Plan, and (B) in
       any transaction in which the shares issued are not eligible for sale in
       the public market during such 90 day period.
 
    5.  COSTS AND EXPENSES.  The Company will pay all costs, expenses and fees
incident to the performance of the obligations of the Company under this
Agreement, including, without limiting the generality of the foregoing, the
following: accounting fees of the Company; the fees and disbursements of counsel
for the Company; the cost of printing and delivering to, or as requested by, the
Underwriters copies of the Registration Statement, Preliminary Prospectuses, the
Prospectus, this Agreement, the Master Agreement Among Underwriters, the
Underwriters' Selling Memorandum, the Underwriters' Questionnaire, the
Invitation Letter, the Blue Sky Survey and any supplements or amendments
thereto; the filing fees of the Commission; the filing fees and expenses
incident to securing any required review by the NASD of the terms of the sale of
the Shares; the listing fee of the Nasdaq National Market; and the expenses,
including the fees and disbursements of counsel for the Underwriters, incurred
in connection with the qualification of the Shares under state securities or
blue sky laws. Any transfer taxes imposed on the sale of the shares to the
several Underwriters will be paid by the Company. The Company shall not,
however, be required to pay for any of the Underwriters' expenses (other than
those related to qualification under state securities or blue sky laws) except
that, if this Agreement shall not be consummated because the conditions in
Section 7 hereof are not satisfied, or because this Agreement is terminated by
the Representatives pursuant to Section 6 hereof, or by reason of any failure,
refusal or inability on the part of the Company to perform any undertaking or
satisfy any condition of this Agreement or to comply with any of the terms
hereof on the Company's part to be performed, unless such failure to satisfy
said
 
                                       9
<PAGE>
condition or to comply with said terms be due to the default or omission of any
Underwriter, then the Company shall reimburse the several Underwriters for
reasonable out-of-pocket expenses, including fees and disbursements of counsel,
reasonably incurred in connection with investigating, marketing and proposing to
market the Shares or in contemplation of performing their obligations hereunder;
but the Company shall not in any event be liable to any of the several
Underwriters for damages on account of loss of anticipated profits from the sale
by them of the Shares.
 
    6.  CONDITIONS OF OBLIGATIONS OF THE UNDERWRITERS.  The several obligations
of the Underwriters to purchase the Firm Shares on the Closing Date and the
Option Shares, if any, on the Option Closing Date are subject to the accuracy,
as of the Closing Date or the Option Closing Date, as the case may be, of the
representations and warranties of the Company contained herein, and to the
performance by the Company of its covenants and obligations hereunder and to the
following additional conditions:
 
        (a) No stop order suspending the effectiveness of the Registration
    Statement, as amended from time to time, shall have been issued and no
    proceedings for that purpose shall have been taken or, to the knowledge of
    the Company, shall be contemplated by the Commission.
 
        (b) The Representatives shall have received on the Closing Date or the
    Option Closing Date, as the case may be, the opinion of Wilson, Sonsini,
    Goodrich & Rosati, Professional Corporation, counsel for the Company, dated
    the Closing Date or the Option Closing Date, as the case may be, addressed
    to the Underwriters to the effect that:
 
            (i) The Company has been duly organized and is validly existing as a
       corporation in good standing under the laws of the State of Delaware,
       with full corporate power and authority to own its properties and conduct
       its business as described in the Prospectus, and the Company is duly
       qualified to transact business in all jurisdictions in which the
       ownership and leasing of property or the conduct of their business
       requires such qualification, except where the failure so to qualify would
       not have a material adverse effect upon the business, condition
       (financial or other) of the Company. The Company has full corporate power
       and authority to own its properties and conduct its business as described
       in the Prospectus.
 
            (ii) The Company has authorized and outstanding capital stock as set
       forth under the caption "Capitalization" in the Prospectus as of the
       dates stated therein, and such counsel shall specify the number of shares
       of Common Stock issued and outstanding as of the date of such opinion;
       the authorized shares of its Capital Stock have been duly authorized; all
       of the outstanding shares of its Common Stock and Preferred Stock have
       been duly authorized and validly issued and are fully paid and
       non-assessable; the Shares (including the Firm Shares and Option Shares,
       if any) to be sold by the Company pursuant to this Agreement have been
       duly authorized and, when issued and paid for as contemplated by this
       Agreement, will be validly issued, fully paid and non-assessable; no
       preemptive rights of shareholders set forth in the Company's Certificate
       of Incorporation or, to the knowledge of such counsel, similar
       contractual rights to purchase, exist with respect to any of the Shares
       or the issue and sale thereof; and, to the knowledge of such counsel, no
       registration rights exist with respect to the capital stock of the
       Company which have not been satisfied or waived in connection with the
       offering of the Shares; the public offering contemplated hereby will
       cause a conversion of the outstanding shares of Preferred Stock into
       Common Stock pursuant to the Company's Certificate of Incorporation; all
       necessary and proper corporate proceedings have been taken in order to
       validly authorize the Common Stock issuable upon the conversion of such
       Preferred Stock into Common Stock, and no further approval or authority
       of the stockholders or the Board of Directors of the Company is required
       for the sale of the Shares to be sold by the Company as contemplated
       hereby.
 
           (iii) All of the Shares conform in all material respects to the
       description thereof contained in the Prospectus, and the certificates
       evidencing the Shares are in due and proper form under the Delaware
       General Corporation Law.
 
                                       10
<PAGE>
           (iv) Except as specifically disclosed in the Registration Statement
       and the financial statements of the Company, and the related notes
       thereto, to such counsel's knowledge, the Company does not have
       outstanding any options to purchase, or any preemptive rights or other
       rights to subscribe for or to purchase, any securities or obligations
       convertible into, or any contracts or commitments to issue or sell shares
       of its capital stock or any such options, rights, convertible securities
       or obligations. The descriptions of the Company's stock option and other
       stock-based plans set forth in the Prospectus are accurate summaries and
       fairly present in all material respects the information required to be
       shown with respect to such plans and rights.
 
            (v) The Registration Statement has become effective under the Act
       and, to the knowledge of such counsel, any required filing of the
       Prospectus and any supplement thereto pursuant to the Rules and
       Regulations has been made in the manner and within the time period
       required by such Rule 424(b).
 
           (vi) The Registration Statement, the Prospectus, the Incorporated
       Documents and each amendment or supplement thereto comply as to form in
       all material respects with the requirements of the Act or the Exchange
       Act, as applicable, and the applicable Rules and Regulations thereunder
       (except that such counsel need express no opinion as to (A) the financial
       statements, notes thereto and related schedules and other financial
       information and statistical data included therein or (B) any information
       furnished in writing by or through the Representatives specifically for
       use in the preparation thereof).
 
           (vii) The statements incorporated by reference into the Registration
       Statement and the Prospectus insofar as such statements constitute a
       summary of documents referred to therein or matters of law, are in all
       material respects, accurate summaries and fairly and correctly present
       the information called for with respect to such documents and matters of
       law.
 
          (viii) Such counsel does not know of any contracts or documents
       required to be filed as exhibits to the Registration Statement or
       described in the Registration Statement or the Prospectus or incorporated
       by reference which are not so filed, or described as required, and such
       contracts and documents as are described in the Registration Statement,
       the Prospectus or the Incorporated Documents are accurately described in
       all material respects.
 
           (ix) To such counsel's knowledge, there is no legal action, suit or
       proceeding pending or threatened against the Company of a character
       required to be disclosed in the Registration Statement, the Prospectus or
       the Incorporated Documents pursuant to the Act and the Rules and
       Regulations or the Exchange Act, as applicable; to such counsel's
       knowledge, the Company is not a party or subject to provisions of any
       injunction, judgment, decree or order of any court, regulatory body,
       administrative agency or other governmental body or agency the effect of
       which could be material and adverse to the business, condition (financial
       or otherwise) or results of operations of the Company.
 
            (x) To such counsel's knowledge, the execution, delivery and
       performance of this Agreement and the consummation of the transactions
       herein contemplated do not and will not: (a) violate any of the
       provisions of the Certificate of Incorporation or bylaws of the Company;
       (b) to such counsel's knowledge, violate any material statute,
       injunction, judgment, order, decree, rule or regulation of any court or
       any governmental, regulatory or administrative body or agency having
       jurisdiction over the Company or any of its property (other than as may
       be required by the NASD with respect to compensation of underwriters or
       as required by state securities or Blue Sky laws as to which such counsel
       need express no opinion); and (c) conflict with or result in the breach
       of, or violation of, any of the terms or provisions of, or constitute,
       either by itself or with the giving of notice or the passage of time or
       both, a default under, any agreement, mortgage, deed of trust, lease,
       franchise, license, indenture, permit or other instrument known to such
       counsel to which the Company is a party or by which the Company or any
 
                                       11
<PAGE>
       of its property known to such counsel is or may be bound or affected,
       except where such breach, violation or default would not have material
       adverse effect on the business, financial condition or results of
       operations of the Company.
 
           (xi) The Company has the corporate power and authority to enter into
       this agreement and to perform the transactions contemplated hereby. This
       Agreement has been duly authorized, executed and delivered by the
       Company.
 
           (xii) No approval, consent, order, authorization, designation,
       declaration or filing by or with any regulatory, administrative or other
       governmental body is necessary in connection with the execution and
       delivery of this Agreement and the consummation of the transactions
       herein contemplated (other than as may be required by the NASD with
       respect to compensation of the Underwriters and compliance with
       Regulation M of the Exchange Act or as required by state securities and
       blue sky laws as to which such counsel need express no opinion) except
       such as have been obtained or made and are in full force and effect,
       specifying the same.
 
           In rendering such opinion, such counsel may rely as to matters
       governed by laws other than the General Corporation Law of the State of
       Delaware, the laws of the State of California and the federal laws of the
       United States, on local counsel in such jurisdictions, PROVIDED that in
       each case such counsel shall state that they believe that they and the
       Underwriters are justified in relying on such other counsel. In addition
       to the matters set forth above, such opinion shall also include a
       statement to the effect that nothing has come to the attention of such
       counsel which causes them to believe that the Registration Statement, or
       any amendment thereto, at the time the Registration Statement or
       amendment became effective, contained an untrue statement of a material
       fact or omitted to state a material fact required to be stated therein or
       necessary to make the statements therein not misleading, or that the
       Prospectus or any amendment or supplement thereto, at the time it was
       filed pursuant to Rule 424(b) or at the Closing Date or the Option
       Closing Date, as the case may be, contained an untrue statement of a
       material fact or omitted to state a material fact required to be stated
       therein or necessary to make the statements therein, in light of the
       circumstances under which they were made, not misleading (except that
       such counsel need express no view as to financial statements, notes
       thereto and related schedules and the other financial information and
       statistical data included therein or information supplied by the
       Underwriters for use therein). With respect to such statement, such
       counsel may state that their belief is based upon the procedures set
       forth in their opinion, but is without independent check and
       verification.
 
        (c) The Representatives shall have received on the Closing Date or the
    Option Closing Date, as the case may be, the opinion of Hogan &. Hartson,
    LLP, special regulatory counsel for the Company, dated the Closing Date or
    the Option Closing Date, as the case may be, addressed to the Underwriters
    to the effect that the statements in the Prospectus under the captions "Risk
    Factors--Government Regulation," "Risk Factors--Uncertainty Relating to
    Third Party Reimbursement," "Business-- Government Regulation--United
    States," and "Business--Third Party Reimbursement," insofar as such
    statements purport to summarize applicable provisions of the Federal Food,
    Drug, and Cosmetic Act, as amended, and the regulations promulgated
    thereunder, and Title XVIII of the Social Security Act, as amended, and the
    regulations promulgated thereunder, have been reviewed by such counsel and
    are accurate summaries in all material respects of the provisions purported
    to be summarized under such captions in the Prospectus. In rendering such
    opinion, such counsel may state that they have not independently verified
    nor do they take any responsibility for nor are they addressing in any way
    any advents of fact, any statements concerning state or foreign law or any
    legal conclusions or statements of belief attributable to the Company.
 
        (d) The Representatives shall have received on the Closing Date or the
    Option Closing Date, as the case may be, the opinion of Medical Technology
    Consultants Europe Ltd., special international regulatory counsel for the
    Company dated the Closing Date or the Option Closing Date, as the case may
    be, addressed the Underwriters, to the effect that the statements in the
    Registration Statement
 
                                       12
<PAGE>
    and the Prospectus under the captions "Risk Factors--Government Regulation"
    and "Business-- Government Regulation--International," insofar as such
    statements purport to summarize applicable provisions of international
    regulatory requirements have been reviewed by such counsel and are accurate
    summaries in all material respects of the provisions purported to be
    summarized under such captions in the Registration Statement and the
    Prospectus. In rendering such opinion, such counsel may state that they have
    not independently verified nor do they take any responsibility for nor are
    they addressing in any way any advents of fact, any statements concerning
    state or foreign law or any legal conclusions or statements of belief
    attributable to the Company.
 
        (e) The Representatives shall have received on the Closing Date or the
    Option Closing Dated, as the case may be, the opinion of Townsend and
    Townsend and Crew, special patent counsel for the Company, dated the Closing
    Date or the Option Closing Date, as the case may be, addressed to the
    Underwriters to the effect that:
 
            (i) The statements in the Registration Statement under the captions
       "Risk Factors-- Reliance on Patents and Protection of Proprietary
       Technology" and Business--Patents and Proprietary Rights" and other
       statements in the Registration Statement and Prospectus that discuss
       patents, patent rights and other proprietary rights, to the extent that
       they constitute matters of law, summaries of legal matters, documents or
       proceedings, or legal conclusions, are accurate and complete statements
       or summaries of the matters therein set forth.
 
            (ii) Such counsel is not aware of any patent, patent right or other
       proprietary right of others which would prevent the conduct of the
       business of the Company now being or currently proposed to be conducted
       by the Company as described in the Prospectus; and such counsel is not
       aware of any rights of third parties to, or any infringement by third
       parties of, any of the Company's patents, patent rights or other
       proprietary rights.
 
           (iii) To such counsel's knowledge, there is no pending or threatened
       action, suit, proceeding or claim by others, either domestically or
       internationally, that the Company is violating any patents, patent
       rights, rights thereto or other proprietary rights of others; or
       otherwise challenging the validity or scope of any such patents, patent
       rights, rights, patent rights and other proprietary rights thereto of
       others or other proprietary rights.
 
           In addition, such counsel shall state that, although they have not
       verified the accuracy or completeness of the statements contained in the
       Registration Statement or the Prospectus, nothing has come to the
       attention of such counsel that caused them to believe that, at the time
       the Registration Statement became effective the description of the
       Company's patents, patent rights and other proprietary rights matters and
       the statements made under the captions "Risk Factors--Reliance on Patents
       and Protection of Proprietary Rights" and "Business--Patents and
       Proprietary Rights" in the Registration Statements and Prospectus
       contained any untrue statement of a material fact or omitted to state a
       material fact required to be stated therein or necessary to make the
       statements therein not misleading, or at the Closing Date or the Option
       Closing Date, as the case may be, the description of the patent, patent
       rights and other proprietary rights, situation of the Company and the
       statements made under the captions "Risk Factors--Reliance on Patents and
       Protection of Proprietary Rights" and Business--Patents and Proprietary
       Rights" in the Registration Statement and Prospectus contained any untrue
       statement of a material fact or omitted to state a material fact required
       to be stated therein or necessary to make the statements made therein, in
       the light of the circumstances under which they were made, not
       misleading.
 
        (f) The Representatives shall have received from Venture Law Group, A
    Professional Corporation, counsel for the Underwriters, an opinion dated the
    Closing Date or the Option Closing Date, as the case may be, substantially
    to the effect that: (i) the Company is a validly organized and existing
    corporation under the laws of the State of Delaware, with corporate power
    and corporate authority to own its property and conduct its business as
    described in the Prospectus; (ii) the authorized shares of the Company's
    Common Stock have been duly authorized; the outstanding shares of the
 
                                       13
<PAGE>
    Company's Common Stock, have been duly authorized and will be validly issued
    and are fully paid and non-assessable; all of the Shares conform to the
    description thereof contained in the Prospectus; the shares of Common Stock
    including the Option Shares, if any, to be sold by the Company pursuant to
    this Agreement have been duly authorized and will be validly issued, fully
    paid and nonassessable when issued and paid for as contemplated by this
    Agreement; (iii) the Registration Statement has become effective under the
    Act, and to such counsel's knowledge, no stop order proceedings with respect
    thereto have been instituted or are pending or threatened under the Act;
    (iv) the Registration Statement, all Preliminary Prospectuses, the
    Prospectus and each amendment or supplement thereto comply as to form in all
    material respects with the requirements of the Act and the applicable Rules
    and Regulations thereunder (except that such counsel need express no opinion
    as to the financial statements, notes thereto and related schedules and the
    other financial information and statistical data included therein); and (v)
    this Agreement has been duly authorized, executed and delivered by the
    Company. In addition to the matters set forth above, such opinion shall also
    include a statement to the effect that nothing has come to the attention of
    such counsel which causes them to believe that the Registration Statement,
    the Prospectus or any amendment thereto contains 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, or that
    the Prospectus or any amendment or supplement thereto, at the time it was
    filed pursuant to Rule 424(b) or at the Closing Date or the Option Closing
    Date, as the case may be, contained an untrue statement of a material fact
    or omitted to state a material fact required to be stated therein or
    necessary to make the statements therein, in light of the circumstances
    under which they were made, not misleading (except that such counsel need
    express no view as to the financial statements, notes thereto and related
    schedules and the other financial information and statistical data included
    therein). With respect to such statement, such counsel may state that their
    belief is based upon the procedures set forth therein, but is without
    independent check and verification.
 
        (g) The Representatives shall have received at or prior to the Closing
    Date from Venture Law Group, A Professional Corporation, a memorandum or
    summary, in form and substance satisfactory to the Representatives, with
    respect to the qualification for offering and sale by the Underwriters of
    the Shares under the state securities or blue sky laws of such jurisdictions
    as the Representatives may reasonably have designated to the Company.
 
        (h) The Representatives shall have received on the effective date of the
    Registration Statement, the Closing Date or the Option Closing Date, as the
    case may be, a signed letter from Ernst & Young LLP, dated the effective
    date of the Registration Statement, the Closing Date or the Option Closing
    Date, as the case may be, which shall confirm, on the basis of a review in
    accordance with the procedures set forth in the letter signed by such firm
    and dated and delivered to the Representatives on the date hereof, that
    nothing has come to their attention during the period from the date five
    days prior to the date hereof, to a date not more than five days prior to
    the Closing Date or the Option Closing Date, as the case may be, which would
    require any change in their letter dated the date hereof if it were required
    to be dated and delivered on the Closing Date or the Option Closing Date, as
    the case may be. All such letters shall be in form and substance
    satisfactory to the Representatives.
 
        (i) The Representatives shall have received on the Closing Date or the
    Option Closing Date, as the case may be, a certificate or certificates of
    the Chief Executive Officer and the Chief Financial Officer of the Company
    to the effect that, as of the Closing Date or the Option Closing Date, as
    the case may be, each of them as an officer of the Company severally
    represents as follows:
 
           (A) The Registration Statement has become effective under the Act and
       no stop order suspending the effectiveness of the Registration Statement
       has been issued, and, to his knowledge, no proceedings for such purpose
       have been taken or are contemplated by the Commission.
 
           (B) He does not know of any litigation instituted or threatened
       against the Company of a character required to be disclosed in the
       Registration Statement which is not so disclosed; he
 
                                       14
<PAGE>
       does not know of any material contract required to be filed as an exhibit
       to the Registration Statement or the Incorporated Documents, which is not
       so filed; and the representations and warranties of the Company contained
       in Section 1 hereof are true and correct as of the Closing Date or the
       Option Closing Date, as the case may be.
 
           (C) When the Registration Statement became effective and at all times
       subsequent thereto up to the delivery of such certificate, the
       Registration Statement and the Prospectus, and any amendments or
       supplements thereto and the Incorporated Documents, when such
       Incorporated Documents became effective or were filed with the
       Commission, contained all material information required to be included
       therein by the Act and the Rules and Regulations or the Exchange Act and
       the applicable rules and regulations of the Commission thereunder, as the
       case may be, and in all material respects conformed to the requirements
       of the Act and the Rules and Regulations or the Exchange Act and the
       applicable rules and regulations of the Commission thereunder, as the
       case may be, the Registration Statement, and any amendment or supplement
       thereto, did not and does not include any untrue statement of a material
       fact or omit to state a material fact required to be stated therein or
       necessary to make the statements therein not misleading, the Prospectus,
       and any amendment or supplement thereto, did not and does not include any
       untrue statement of a material fact or omit to state a material fact
       necessary to make the statements therein, in the light of the
       circumstances under which they were made, not misleading, and, since the
       effective date of the Registration Statement, there has occurred no event
       required to be set forth in an amended or supplemented Prospectus which
       has not been so set forth; and
 
           (D) Subsequent to the respective dates as of which information is
       given in the Registration Statement and Prospectus, there has not been
       (a) any material adverse change in the condition (financial or
       otherwise), earnings, operations, business or business prospects of the
       Company and its subsidiaries considered as one enterprise, (b) any
       transaction that is material to the Company and its subsidiaries
       considered as one enterprise, except transactions entered into in the
       ordinary course of business, (c) any obligation, direct or contingent,
       that is material to the Company and its subsidiaries considered as one
       enterprise, incurred by the Company or its subsidiaries, except
       obligations incurred in the ordinary course of business, (d) any change
       in the capital stock or outstanding indebtedness of the Company or any of
       its subsidiaries that is material to the Company and its subsidiaries
       considered as one enterprise, (e) any dividend or distribution of any
       kind declared, paid or made on the capital stock of the Company or any of
       its subsidiaries, or (f) any loss or damage (whether or not insured) to
       the property of the Company or any of its subsidiaries which has been
       sustained or will have been sustained which has a material adverse effect
       on the condition (financial or otherwise), earnings, operations, business
       or business prospects of the Company and its subsidiaries considered as
       one enterprise.
 
        (j) The Company shall have furnished to the Representatives such further
    certificates and documents confirming the representations and warranties
    contained herein and related matters as the Representatives may reasonably
    have requested.
 
        (k) The Firm Shares and the Option Shares, if any, have been approved
    for quotation on the Nasdaq National Market.
 
        (l) You shall have received on the Closing Date and on any later date on
    which Option Shares are to be purchased, as the case may be, a letter from
    Ernst & Young LLP addressed to the Company and the Underwriters, dated the
    Closing Date or such later date on which Option Shares are to be purchased,
    as the case may be, confirming that they are independent certified public
    accountants with respect to the Company within the meaning of the Act and
    the applicable published Rules and Regulations and based upon the procedures
    described in such letter delivered to you concurrently with the execution of
    this Agreement (herein called the "Original Letter"), but carried out to a
    date not more than five (5) business days prior to the Closing Date or such
    later date on which Option Shares are to be purchased, as the case may be,
    (i) confirming, to the extent true, that the statements
 
                                       15
<PAGE>
    and conclusions set forth in the Original Letter are accurate as of the
    Closing Date or such later date on which Option Shares are to be purchased,
    as the case may be, and (ii) setting forth any revisions and additions to
    the statements and conclusions set forth in the Original Letter which are
    necessary to reflect any changes in the facts described in the Original
    Letter since the date of such letter, or to reflect the availability of more
    recent financial statements, data or information. The letter shall not
    disclose any change in the condition (financial or otherwise), earnings,
    operations, business or business prospects of the Company and its
    subsidiaries considered as one enterprise from that set forth in the
    Registration Statement or Prospectus, which, in your sole judgment, is
    material and adverse and that makes it, in your sole judgment, impracticable
    or inadvisable to proceed with the public offering of the Shares as
    contemplated by the Prospectus. The Original Letter from Ernst & Young LLP
    shall be addressed to or for the use of the Underwriters in form and
    substance satisfactory to the Underwriters and shall (i) represent, to the
    extent true, that they are independent certified public accountants with
    respect to the Company within the meaning of the Act and the applicable
    published Rules and Regulations, (ii) set forth their opinion with respect
    to their examination of the balance sheets of the Company for the periods
    from inception to March 31, 1993 and for the periods for years ended March
    31, 1994 to March 31, 1997 and related statements of operations,
    shareholders' equity, and cash flows for the periods from inception to 1993
    and for the twelve (12) months each of the periods ended March 31, 1994 to
    March 31, 1997, (iii) state that Ernst & Young LLP has performed the
    procedure set out in Statement on Auditing Standards No. 71 ("SAS 71") for a
    review of interim financial information and providing the report of Ernst &
    Young LLP as described in SAS 71 on the financial statements for each of the
    quarters ended September 30, 1996 and 1997, and (iv) address other matters
    agreed upon by Ernst & Young LLP and you. In addition, you shall have
    received from Ernst & Young LLP a letter addressed to the Company and made
    available to you for the use of the Underwriters stating that their review
    of the Company's system of internal accounting controls, to the extent they
    deemed necessary in establishing the scope of their examination of the
    Company's financial statements as of March 31,     , did not disclose any
    weaknesses in internal controls that they considered to be material
    weaknesses.
 
    The opinions and certificates mentioned in this Agreement shall be deemed to
be in compliance with the provisions hereof only if they are in all material
respects satisfactory to the Representatives and to Venture Law Group, A
Professional Corporation, counsel for the Underwriters.
 
    If any of the conditions herein above provided for in this Section 6 shall
not have been fulfilled when and as required by this Agreement to be fulfilled,
the obligations of the Underwriters hereunder may be terminated by the
Representatives by notifying the Company of such termination in writing or by
telegram at or prior to the Closing Date or the Option Closing Date, as the case
may be.
 
    In such event, the Company and the Underwriters shall not be under any
obligation to each other (except to the extent provided in Sections 5 and 8
hereof).
 
    7.  CONDITIONS OF THE OBLIGATIONS OF THE COMPANY.  The obligations of the
Company to sell and deliver the portion of the Shares required to be delivered
as and when specified in this Agreement are subject to the conditions that at
the Closing Date or the Option Closing Date, as the case may be, no stop order
suspending the effectiveness of the Registration Statement shall have been
issued and in effect or proceedings therefor initiated or threatened.
 
    8.  INDEMNIFICATION.
 
        (a) The Company agrees to indemnify and hold harmless each Underwriter
    and each person, if any, who controls any Underwriter within the meaning of
    the Act against any losses, claims, damages or liabilities to which such
    Underwriter or such controlling person may become subject under the Act or
    the Exchange Act or otherwise, insofar as such losses, claims, damages or
    liabilities (or actions or proceedings in respect thereof) arise out of or
    are based upon (i) any untrue statement or alleged untrue statement of any
    material fact contained in or incorporated by reference into the
    Registration Statement, any Preliminary Prospectus, the Prospectus or any
    amendment or supplement thereto, or (ii) the omission or alleged omission to
    state therein a material fact required to be stated therein or
 
                                       16
<PAGE>
    necessary to make the statements therein not misleading, and will reimburse
    each Underwriter and each such controlling person for any legal or other
    expenses reasonably incurred by such Underwriter or such controlling person
    in connection with investigating or defending any such loss, claim, damage,
    liability, action or proceeding; PROVIDED, HOWEVER, that (i) the Company
    will not be liable in any such case to the extent that any such loss, claim,
    damage or liability arises out of or is based upon an untrue statement or
    alleged untrue statement, or omission or alleged omission, made in or
    incorporated by reference into the Registration Statement, any Preliminary
    Prospectus, the Prospectus, or any such amendment or supplement, in reliance
    upon and in conformity with written information furnished to the Company by
    or through the Representatives specifically for use in the preparation
    thereof (which the parties hereto agree is limited solely to that
    information contained on the cover page of the Preliminary Prospectus or
    Prospectus or in the section thereof entitled "Underwriting"); and (ii) that
    the Company shall not be liable to any Underwriter with respect to any
    Preliminary Prospectus to the extent that any loss, claim, damage or
    liability of such Underwriter results from the fact that such Underwriter
    sold Shares to a person to whom there was not given or sent, at or prior to
    the written confirmation of such sale, a copy of the Prospectus or of the
    Prospectus as then amended or supplemented in any case where such delivery
    is required by the Act if the Company has previously furnished copies
    thereof to such Underwriter and the loss, claim, damage or liability of such
    Underwriter results from an untrue statement or omission of a material fact
    contained in the Preliminary Prospectus which was corrected in the
    Prospectus (or the Prospectus as amended or supplemented). This indemnity
    agreement will be in addition to any liability which the Company may
    otherwise have.
 
        (b) Each Underwriter will indemnify and hold harmless the Company, each
    of its directors, each of its officers who have signed the Registration
    Statement and each person, if any, who controls the Company within the
    meaning of the Act, against any losses, claims, damages or liabilities to
    which the Company or any such director, officer or controlling person may
    become subject under the Act or the Exchange Act or otherwise, insofar as
    such losses, claims, damages or liabilities (or actions or proceedings in
    respect thereof) arise out of or are based upon any untrue statement or
    alleged untrue statement of any material fact contained in or incorporated
    by reference into the Registration Statement, any Preliminary Prospectus,
    the Prospectus or any amendment or supplement thereto, or arise out of or
    are based upon the omission or the 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 any legal or other
    expenses reasonably incurred by the Company or any such director, officer or
    controlling person in connection with investigating or defending any such
    loss, claim, damage, liability, action or proceeding; PROVIDED, HOWEVER,
    that each Underwriter will be liable in each case to the extent, but only to
    the extent, that such untrue statement or alleged untrue statement or
    omission or alleged omission has been made in or incorporated by reference
    into the Registration Statement, any Preliminary Prospectus, the Prospectus
    or such amendment or supplement, in reliance upon and in conformity with
    written information furnished to the Company by or through the
    Representatives specifically for use in the preparation thereof (which the
    parties hereto agree is limited solely to that information contained on the
    cover page of the Preliminary Prospectus or Prospectus or in the section
    thereof entitled "Underwriting"). This indemnity agreement will be in
    addition to any liability which such Underwriter may otherwise have.
 
        (c) In case any proceeding (including any governmental investigation)
    shall be instituted involving any person in respect of which indemnity may
    be sought pursuant to this Section 8, such person (the "indemnified party")
    shall promptly notify the person against whom such indemnity may be sought
    (the "indemnifying party") in writing. No indemnification provided for in
    Section 8(a) or (b) shall be available to any party who shall fail to give
    notice as provided in this Section 8(c) if the party to whom notice was not
    given was unaware of the proceeding to which such notice would have related
    and was prejudiced by the failure to give such notice, but the failure to
    give such notice shall not relieve the indemnifying party or parties from
    any liability which it or they may have to the indemnified party for
    contribution or otherwise than on account of the provisions of Section 8(a)
    or (b). In case any such proceeding shall be brought against any indemnified
    party and it shall notify the
 
                                       17
<PAGE>
    indemnifying party of the commencement thereof, the indemnifying party shall
    be entitled to participate therein and, to the extent that it shall wish,
    jointly with any other indemnifying party similarly notified, to assume the
    defense thereof, with counsel satisfactory to such indemnified party (in the
    reasonable judgment of such indemnified party) and shall pay as incurred the
    fees and disbursements of such counsel related to such proceeding. In any
    such proceeding, any indemnified party shall have the right to retain its
    own counsel at its own expense. Notwithstanding the foregoing, the
    indemnifying party shall pay as incurred the fees and expenses of the
    counsel retained by the indemnified party in the event (i) the indemnifying
    party and the indemnified party shall have mutually agreed to the retention
    of such counsel or (ii) the named parties to any such proceeding (including
    any impleaded parties) include both the indemnifying party and the
    indemnified party and representation of both parties by the same counsel
    would be inappropriate due to actual or potential differing interests
    between them (based on advise of counsel to the indemnified party). It is
    understood that the indemnifying party shall not, in connection with any
    proceeding or related proceedings in the same jurisdiction, be liable for
    the reasonable fees and expenses of more than one separate firm for all such
    indemnified parties. Such firm shall be designated in writing by you in the
    case of parties indemnified pursuant to Sections 8(a) and by the Company in
    the case of parties indemnified pursuant to Section 8(b). The indemnifying
    party shall not be liable for any settlement of any proceeding effected
    without its written consent, but if settled with such consent or if there be
    a final judgment for the plaintiff, the indemnifying party agrees to
    indemnify the indemnified party from and against any loss or liability by
    reason of such settlement or judgment.
 
        (d) If the indemnification provided for in this Section 8 is unavailable
    to or insufficient to hold harmless an indemnified party under Section 8(a)
    or (b) above in respect of any losses, claims, damages or liabilities (or
    actions or proceedings in respect thereof) referred to therein, then each
    indemnifying party shall contribute to the amount paid or payable by such
    indemnified party as a result of such losses, claims, damages or liabilities
    (or actions or proceedings in respect thereof) in such proportion as is
    appropriate to reflect the relative benefits received by the Company on the
    one hand and the Underwriters on the other from the offering of the Shares.
    If, however, the allocation provided by the immediately preceding sentence
    is not permitted by applicable law or if the indemnified party failed to
    give the notice required under Section 8(c) above, then each indemnifying
    party shall contribute to such amount paid or payable by such indemnified
    party in such proportion as is appropriate to reflect not only such relative
    benefits but also the relative fault of the Company on the one hand and the
    Underwriters on the other in connection with the statements or omissions
    which resulted in such losses, claims, damages or liabilities (or actions or
    proceedings in respect thereof), as well as any other relevant equitable
    considerations. The relative benefits received by the Company on the one
    hand and the Underwriters on the other shall be deemed to be in the same
    proportion as the total net proceeds from the offering (before deducting
    expenses) received by the Company bears to the total underwriting discounts
    and commissions received by the Underwriters, in each case as set forth in
    the table on the cover page of the Prospectus. The relative fault shall be
    determined by reference to, among other things, whether the untrue or
    alleged untrue statement of a material fact or the omission or alleged
    omission to state a material fact relates to information supplied by the
    Company on the one hand or the Underwriters on the other and the parties'
    relative intent, knowledge, access to information and opportunity to correct
    or prevent such statement or omission.
 
        The Company and the Underwriters agree that it would not be just and
    equitable if contributions pursuant to this Section 8(d) were determined by
    pro rata allocation (even if the Underwriters were treated as one entity for
    such purpose) or by any other method of allocation which does not take
    account of the equitable considerations referred to above in this Section
    8(d). The amount paid or payable by an indemnified party as a result of the
    losses, claims, damages or liabilities (or actions or proceedings in respect
    thereof) referred to above in this Section 8(d) shall be deemed to include
    any legal or other expenses reasonably incurred by such indemnified party in
    connection with investigating or defending any such action or claim.
    Notwithstanding the provisions of this Subsection (d), (i) no Underwriter
    shall be required to contribute any amount in excess of the underwriting
 
                                       18
<PAGE>
    discounts and commissions applicable to the Shares purchased by such
    Underwriter, and (ii) no person guilty of fraudulent misrepresentation
    (within the meaning of Section 11(f) of the Act) shall be entitled to
    contribution from any person who was not guilty of such fraudulent
    misrepresentation. The Underwriters' obligations in this Section 8(d) to
    contribute are several in proportion to their respective underwriting
    obligations and not joint.
 
        (e) In any proceeding relating to the Registration Statement, any
    Preliminary Prospectus, the Prospectus or any supplement or amendment
    thereto, including any document incorporated by reference therein, each
    party against whom contribution may be sought under this Section 8 hereby
    consents to the jurisdiction of any court having jurisdiction over any other
    contributing party, agrees that process issuing from such court may be
    served upon him or it by any other contributing party and consents to the
    service of such process and agrees that any other contributing party may
    join him or it as an additional defendant in any such proceeding in which
    such other contributing party is a party.
 
    9.  DEFAULT BY UNDERWRITERS.  If on the Closing Date or the Option Closing
Date, as the case may be, any Underwriter shall fail to purchase and pay for the
portion of the Shares which such Underwriter has agreed to purchase and pay for
on such date (otherwise than by reason of any default on the part of the
Company), you, as Representatives of the Underwriters, shall use your best
efforts to procure within 24 hours thereafter one or more of the other
Underwriters, or any others, to purchase from the Company such amounts as may be
agreed upon and upon the terms set forth herein, the Firm Shares or Option
Shares, as the case may be, which the defaulting Underwriter or Underwriters
failed to purchase. If during such 24 hours you, as such Representatives, shall
not have procured such other Underwriters, or any others, to purchase the Firm
Shares or Option Shares, as the case may be, agreed to be purchased by the
defaulting Underwriter or Underwriters, then (a) if the aggregate number of
shares with respect to which such default shall occur does not exceed 10% of the
Firm Shares or Option Shares, as the case may be, covered hereby, the other
Underwriters shall be obligated, severally, in proportion to the respective
numbers of Firm Shares or Option Shares, as the case may be, which they are
obligated to purchase hereunder, to purchase the Firm Shares or Option Shares,
as the case may be, which such defaulting Underwriter or Underwriters failed to
purchase, or (b) if the aggregate number of Firm Shares or Option Shares, as the
case may be, with respect to which such default shall occur exceeds 10% of the
Firm Shares or Option Shares, as the case may be, covered hereby, the Company or
you as the Representatives of the Underwriters will have the right, by written
notice given within the next 24-hour period to the parties to this Agreement, to
terminate this Agreement without liability on the part of the nondefaulting
Underwriters or of the Company except to the extent provided in Section 8
hereof. In the event of a default by any Underwriter or Underwriters, as set
forth in this Section 9, the Closing Date or Option Closing Date, as the case
may be, may be postponed for such period, not exceeding seven days, as you, as
Representatives, may determine in order that the required changes in the
Registration Statement or in the Prospectus or in any other documents or
arrangements may be effected. The term "Underwriter" includes any person
substituted for a defaulting Underwriter. Any action taken under this Section 9
shall not relieve any defaulting Underwriter from liability in respect of any
default of such Underwriter under this Agreement.
 
    10.  NOTICES.  All communications hereunder shall be in writing and, except
as otherwise provided herein, will be mailed, delivered or telegraphed and
confirmed as follows: if to the Underwriters to BT Alex. Brown Incorporated, One
South Street, Baltimore, Maryland 21202, Attention: Syndicate; and if to the
Company, to Perclose, Inc., 199 Jefferson Drive, Menlo Park, California,
Attention: Henry A. Plain, Jr.
 
    11.  TERMINATION.  This Agreement may be terminated by you by notice to the
Company as follows:
 
        (a) at any time prior to the earlier of (i) the time the Shares are
    released by you for sale by notice to the Underwriters, or (ii) 11:30 A.M.,
    Baltimore time, on the first business day following the date of this
    Agreement;
 
        (b) at any time prior to the Closing Date if any of the following has
    occurred: (i) since the respective dates as of which information is given in
    the Registration Statement and the Prospectus, any material adverse change
    or any development involving a prospective material adverse change in
 
                                       19
<PAGE>
    or affecting the condition, financial or otherwise, of the Company or the
    earnings, business affairs, or management of the Company, whether or not
    arising in the ordinary course of business, (ii) any outbreak or escalation
    of hostilities or declaration of war or national emergency after the date
    hereof or other national or international calamity or crisis or change in
    economic or political conditions if the effect of such outbreak, escalation,
    declaration, emergency, calamity, crisis or change on the financial markets
    of the United States would, in your reasonable judgment, make the offering
    or delivery of the Shares impracticable, (iii) suspension of trading in
    securities on the New York Stock Exchange or the American Stock Exchange or
    limitation on prices (other than limitations on hours or number of days of
    trading) for securities on either such Exchange, (iv) the enactment,
    publication, decree or other promulgation of any federal or state statute,
    regulation, rule or order of any court or other governmental authority which
    in your reasonable opinion materially and adversely affects or will
    materially or adversely affect the business or operations of the Company,
    (v) declaration of a banking moratorium by either federal or New York State
    authorities, or (vi) the taking of any action by any federal, state or local
    government or agency in respect of its monetary or fiscal affairs which in
    your reasonable opinion has a material adverse effect on the securities
    markets in the United States; or
 
        (c) as provided in Sections 6 and 9 of this Agreement.
 
    This Agreement may also be terminated by you, by notice to the Company, as
to any obligation of the Underwriters to purchase the Option Shares, upon the
occurrence at any time prior to the Option Closing Date of any of the events
described in subparagraph (b) above or as provided in Sections 6 and 9 of this
Agreement.
 
    12.  SUCCESSORS.  This Agreement has been and is made solely for the benefit
of the Underwriters, and the Company and their respective successors, executors,
administrators, heirs and assigns, and the officers, directors and controlling
persons referred to herein, and no other person will have any right or
obligation hereunder. The term "successors" shall not include any purchaser of
the Shares merely because of such purchase.
 
    13.  MISCELLANEOUS.  The reimbursement, indemnification and contribution
agreements contained in this Agreement and the representations, warranties and
covenants in this Agreement shall remain in full force and effect regardless of
(a) any termination of this Agreement, (b) any investigation made by or on
behalf of any Underwriter or controlling person thereof, or by or on behalf of
the Company or its directors or officers and (c) delivery of and payment for the
Shares under this Agreement.
 
    This Agreement may be executed in two or more counterparts, each of which
shall be deemed an original, but all of which together shall constitute one and
the same instrument.
 
    This Agreement shall be governed by, and construed in accordance with, the
laws of the State of California.
 
                                       20
<PAGE>
    If the foregoing letter is in accordance with your understanding of our
agreement, please sign and return to us the enclosed duplicates hereof,
whereupon it will become a binding agreement among the Company and the several
Underwriters in accordance with its terms.
 
                                          Very truly yours,
                                          PERCLOSE, INC.
                                          By:
                                             -----------------------------------
                                             Henry A. Plain, Jr.
                                             President and Chief Executive
                                          Officer
 
The foregoing Underwriting Agreement
is hereby confirmed and accepted as of
the date first above written.
 
BT ALEX. BROWN INCORPORATED
PIPER JAFFRAY INC.
As Representatives of the
several Underwriters listed
on Schedule I
 
By: BT ALEX. BROWN INCORPORATED
   By
      --------------------------------
      Authorized Officer
 
                                       21
<PAGE>
                                   SCHEDULE I
                            SCHEDULEOF UNDERWRITERS
 
<TABLE>
<CAPTION>
                                                                                                     NUMBER OF
                                                                                                    FIRM SHARES
UNDERWRITER                                                                                       TO BE PURCHASED
- ------------------------------------------------------------------------------------------------  ----------------
<S>                                                                                               <C>
BT Alex. Brown Incorporated.....................................................................
Piper Jaffray Inc...............................................................................
 
                                                                                                  ----------------
  Total.........................................................................................       1,000,000
                                                                                                  ----------------
                                                                                                  ----------------
</TABLE>

<PAGE>
                                                                     EXHIBIT 5.1
 
                                November 5, 1997
 
Perclose, Inc.
199 Jefferson Drive
Menlo Park, CA 94025
 
                     RE: REGISTRATION STATEMENT ON FORM S-3
 
Ladies and Gentlemen:
 
    We have examined the Registration Statement on Form S-3 filed by you with
the Securities and Exchange Commission (the "Commission") on or about November
5, 1997 (as such may be further amended or supplemented, the "Registration
Statement"), in connection with the registration under the Securities Act of
1933, as amended (the "Act"), of up to 1,150,000 shares of your Common Stock
(the "Shares"). The Shares, which include up to 150,000 shares of Common Stock
issuable pursuant to an over-allotment option granted to the underwriters (the
"Underwriters"), are to be sold to the Underwriters as described in such
Registration Statement for sale to the public. As your counsel in connection
with this transaction, we have examined the proceedings proposed to be taken by
you in connection with the issuance and sale of the Shares.
 
    Based on the foregoing, it is our opinion that, upon conclusion of the
proceedings being taken or contemplated by us, as your counsel, to be taken
prior to the issuance of the Shares and upon completion of the proceedings taken
in order to permit such transactions to be carried out in accordance with the
securities laws of various states where required, the Shares, when issued and
sold in the manner described in the Registration Statement, will be legally and
validly issued, fully paid and nonassessable.
 
    We consent to the use of this opinion as an exhibit to the Registration
Statement, and further consent to the use of our name wherever appearing in the
Registration Statement, including the prospectus constituting a part thereof,
which has been approved by us, as such may be further amended or supplemented,
or incorporated by reference in any Registration Statement relating to the
prospectus file pursuant to Rule 462(b) of the Act.
 
                                          Very truly yours,
 
                                          WILSON SONSINI GOODRICH & ROSATI
                                          Professional Corporation

<PAGE>
                                                                    EXHIBIT 23.1
 
               CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS
 
    We consent to the reference to our firm under the captions "Selected
Financial Data" and "Experts" in the Registration Statement (Form S-3) and
related Prospectus of Perclose, Inc. for the registration of 1,150,000 shares of
its common stock and to the incorporation by reference therein of our reports
dated April 25, 1997, with respect to the financial statements of Perclose, Inc.
incorporated by reference in its Annual Report (Form 10-K) for the year ended
March 31, 1997 and the related financial statement schedule included therein,
filed with the Securities and Exchange Commission.
 
                                                               ERNST & YOUNG LLP
 
San Jose, California
November 3, 1997

<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
       
<S>                             <C>
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          MAR-31-1998
<PERIOD-START>                             APR-01-1997
<PERIOD-END>                               SEP-30-1997
<CASH>                                       2,627,556
<SECURITIES>                                15,355,441
<RECEIVABLES>                                1,331,838
<ALLOWANCES>                                         0
<INVENTORY>                                  1,134,389
<CURRENT-ASSETS>                            21,721,666
<PP&E>                                       4,119,418
<DEPRECIATION>                               2,003,035
<TOTAL-ASSETS>                              24,643,333
<CURRENT-LIABILITIES>                        2,897,094
<BONDS>                                              0
                                0
                                          0
<COMMON>                                         9,626
<OTHER-SE>                                  21,736,613
<TOTAL-LIABILITY-AND-EQUITY>                24,643,333
<SALES>                                      2,379,795
<TOTAL-REVENUES>                             2,379,795
<CGS>                                        3,249,358
<TOTAL-COSTS>                               11,355,245
<OTHER-EXPENSES>                             8,105,887
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                              92,380
<INCOME-PRETAX>                            (8,362,867)
<INCOME-TAX>                                         0
<INCOME-CONTINUING>                        (8,362,867)
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                               (8,362,867)
<EPS-PRIMARY>                                    (.87)
<EPS-DILUTED>                                    (.87)
        

</TABLE>


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