<PAGE>   1

     As filed with the Securities and Exchange Commission on August 24, 1999

                                                      Registration No. 333-72261
================================================================================

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

                               AMENDMENT NO. 4 TO

                                    FORM S-3
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

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

                                  NEOPATH, INC.
             (Exact name of registrant as specified in its charter)

          WASHINGTON                                            91-1436093
(State or other jurisdiction of                              (I.R.S. Employer
 incorporation ororganization)                            Identification Number)

                             8271 - 154TH AVENUE NE
                            REDMOND, WASHINGTON 98052
                                 (425) 869-7284
          (Address, including zip code, and telephone number, including
             area code, of registrant's principal executive offices)

                               RONALD R. BROMFIELD
                      PRESIDENT AND CHIEF EXECUTIVE OFFICER
                                  NEOPATH, INC.
                             8271 - 154TH AVENUE NE
                            REDMOND, WASHINGTON 98052
                                 (425) 869-7284
       (Name, address, including zip code, and telephone number, including
                        area code, of agent for service)

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

                                   Copies to:
                              MICHAEL E. STANSBURY
                                PERKINS COIE LLP
                          1201 THIRD AVENUE, 48TH FLOOR
                         SEATTLE, WASHINGTON 98101-3099
                                 (206) 583-8888

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

Approximate date of commencement of proposed sale to the public: AS SOON AS
   PRACTICABLE AFTER THIS REGISTRATION STATEMENT BECOMES EFFECTIVE.

If the only securities being registered on this Form are being offered pursuant
   to dividend or interest reinvestment plans, please check the following
   box. [ ]

If any of the securities being registered on this Form are to be offered on a
   delayed or continuous basis pursuant to Rule 415 under the Securities Act of
   1933, other than securities offered only in connection with dividend or
   interest reinvestment plans, check the following box. [X]

If this Form is filed to register additional securities for an offering pursuant
   to Rule 462(b) under the Securities Act of 1933, 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 of 1933, 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. [ ] __________

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

     THE REGISTRANT HEREBY UNDERTAKES TO AMEND 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 THIS REGISTRATION STATEMENT
SHALL BECOME EFFECTIVE ON SUCH DATE AS THE SEC, ACTING PURSUANT TO SAID SECTION
8(a), MAY DETERMINE.




<PAGE>   2


The information in this prospectus is not complete and may be changed. The
selling shareholders may not sell these securities until the registration
statement filed with the Securities and Exchange Commission is effective. This
prospectus is not an offer to sell these securities and is not soliciting an
offer to buy these securities in any state where the offer of sale is not
permitted.




                  SUBJECT TO COMPLETION, DATED AUGUST 24, 1999


                                2,900,000 SHARES
                                  NEOPATH, INC.

                                  COMMON STOCK

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

Certain shareholders of NeoPath may offer for sale up to 2,900,000 shares of
common stock at various times at market prices prevailing at the time of sale or
at privately negotiated prices.

NeoPath will not receive any proceeds from the sale of the shares by the selling
shareholders.


The common stock trades on the Nasdaq National Market under the symbol "NPTH."
On August 18, 1999, the last reported sales price of the common stock on Nasdaq
was $3.375 per share.

INVESTING IN THE COMMON STOCK INVOLVES A HIGH DEGREE OF RISK. SEE "RISK FACTORS"
BEGINNING ON PAGE 2.


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

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

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




<PAGE>   3

                                TABLE OF CONTENTS




<TABLE>
<S>                                                                                                                    <C>
ABOUT NEOPATH........................................................................................................   1
AGREEMENT TO MERGE WITH AUTOCYTE.....................................................................................   1
RISK FACTORS.........................................................................................................   2
OTHER RECENT EVENTS..................................................................................................  11
FORWARD-LOOKING INFORMATION..........................................................................................  12
HOW TO OBTAIN MORE INFORMATION.......................................................................................  12
SELLING SHAREHOLDERS.................................................................................................  14
PLAN OF DISTRIBUTION.................................................................................................  15
VALIDITY OF COMMON STOCK.............................................................................................  16
EXPERTS ............................................................................................................   16
</TABLE>



















                                      -i-



<PAGE>   4

                                  ABOUT NEOPATH

         NeoPath develops and markets visual intelligence technology to increase
accuracy in medical testing. NeoPath's initial products include two automated
screening systems that integrate proprietary high-speed morphology computers,
video imaging technology and sophisticated image interpretation software to
capture and analyze thousands of microscopic images from a Pap smear slide for
the early detection of cervical cancer.

         The FDA approved our AutoPap(R) 300 QC Automatic Pap Screener System in
1995. The AutoPap QC is a rescreening device used for quality control and
rescreening of previously screened Pap smear slides. Clinical studies have shown
that the AutoPap QC detects a significantly higher proportion of undetected
abnormal slides than procedures typically employed by clinical laboratories to
meet federal rescreening requirements. These studies were performed by
independent laboratories, and NeoPath funded the studies to support FDA claims.

         The FDA approved our AutoPap(R) Primary Screening System in May 1998.
The AutoPap Primary Screener uses the same hardware components as the AutoPap
QC, but uses enhanced software to perform the initial screening of Pap smear
slides and to classify up to 25% of such slides as requiring no further review.
NeoPath also has funded clinical studies of the effectiveness of the AutoPap
Screener by independent laboratories. These clinical studies have shown that the
AutoPap Primary Screener provides superior sensitivity and specificity when
compared to existing laboratory practice. Currently it is the only instrument
approved by the FDA that allows Pap smear slides to bypass human review. We
believe that this feature of the AutoPap Primary Screener provides customers
with an economic incentive to adopt the technology. The AutoPap Screener
provides customers with the functionality of both the AutoPap QC as well as a
primary screening system; therefore, we are focusing our sales efforts on the
AutoPap Screener.

         The AutoPap System refers to the AutoPap Primary Screener and the
AutoPap QC together.


         AGREEMENT TO MERGE WITH AUTOCYTE


         On June 4, 1999, NeoPath and AutoCyte agreed to a merger in which a
wholly owned subsidiary of AutoCyte will merge with NeoPath, and NeoPath will
become a wholly owned subsidiary of AutoCyte.

         On the effective date of the merger, each issued and outstanding share
of NeoPath common stock will automatically convert into the right to receive
0.7903 shares of AutoCyte common stock. AutoCyte will pay cash in lieu of
issuing fractional shares of AutoCyte common stock. Outstanding employee and
director options and certain warrants to purchase shares of NeoPath common stock
will be converted to AutoCyte options and warrants at the same exchange ratio.
We expect the merger to be a tax-free reorganization and to be accounted for as
a pooling of interests. The parties may terminate the merger agreement in
certain circumstances.

         The shares of our stock that you purchase in this offering will be a
part of the merger with AutoCyte if it is completed. NeoPath and AutoCyte must
still satisfy important conditions before the merger can be completed. In
particular, shareholders of both companies will need to vote to approve the
transaction. We cannot guarantee that the merger will be completed, and
therefore you may not receive shares of AutoCyte common stock. If the merger is
not completed, you will continue to hold any shares of NeoPath common stock you
purchase in the offering.


         We plan to hold a special meeting of shareholders on September 30, 1999
for a vote on the proposed merger. Shareholders of record on September 8, 1999
will be entitled to vote at that meeting. You will not be able to vote the
shares you may acquire in this offering if you purchase them after September 8,
1999.







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<PAGE>   5






                                  RISK FACTORS

IF AUTOCYTE'S STOCK PRICE DECLINES, THE VALUE OF THE MERGER CONSIDERATION TO
         NEOPATH'S SHAREHOLDERS WILL DECLINE.

         Under the merger agreement, each share of our common stock will be
converted into the right to receive 0.7903 shares of AutoCyte common stock. This
exchange ratio is a fixed number and will not be adjusted in the event of any
increase or decrease in the price of AutoCyte common stock or our common stock.
The prices of AutoCyte common stock and our common stock at the closing of the
merger may vary from their respective prices on the date of this prospectus.
These prices may vary because of changes in the business, operations or
prospects of NeoPath or AutoCyte, market assessments of the likelihood that the
merger will be completed, the timing of the completion of the merger, the
prospects of post-merger operations, general market and economic conditions and
other factors. We urge prospective purchasers to obtain current market
quotations for NeoPath common stock and AutoCyte common stock.

AUTOCYTE FACES RISKS THAT MAY CAUSE THE VALUE OF THE AUTOCYTE SHARES YOU MAY
         RECEIVE IN THE MERGER TO DECLINE.


         Upon completion of the merger with AutoCyte, our shareholders,
including you if you purchase NeoPath common stock in this offering, will become
AutoCyte shareholders. Alternatively, if the merger is not completed, you will
continue to own shares of NeoPath common stock that you purchase in this
offering. AutoCyte's business differs from our business and AutoCyte's results
of operations, as well as the price of AutoCyte's common stock, may be affected
by the following factors, which are different from those that would affect our
results of operations and the price of our common stock:

         o  AutoCyte is a young company and has not yet generated any
            significant revenue through the sale of its products. AutoCyte may
            never generate any significant revenue from the sale of its
            products.

         o  AutoCyte has yet to obtain FDA approval for one of its two principal
            products. It may not be able to obtain necessary approvals and,
            therefore, may be unable to successfully market and sell its
            products.

         o  AutoCyte's long-term success depends on market acceptance of its
            principal products as an alternative to conventional pap smears. It
            may never achieve this market acceptance.

         o  AutoCyte plans to manufacture its products, but has limited
            manufacturing experience and capacity.


The effects of any of these risks may cause the value of the AutoCyte shares
that NeoPath shareholders may receive in the merger to decline. For a discussion
of AutoCyte's businesses and certain factors to consider in connection with
these businesses, see AutoCyte's Annual Report on Form 10-K for the year ended
December 31, 1998, as amended, which has been filed with the Securities and
Exchange Commission, and our Annual Report on Form 10-K for the year ended
December 31, 1998. A discussion of additional factors that may affect our
business is set forth below.

THE INFORMATION IN THIS PROSPECTUS IS FORWARD-LOOKING, AND OUR ACTUAL RESULTS
         MAY BE DIFFERENT FROM OUR PREDICTIONS.

         This prospectus and the documents we incorporate by reference contain
forward-looking statements that involve risks and uncertainties. The statements
in this prospectus that are not purely historical are forward-looking







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<PAGE>   6

statements. Words such as "anticipates," "expects," "intends," "plans,"
"believes," "seeks," estimates," and similar expressions identify
forward-looking statements. But the absence of these words does not mean the
statement is not forward-looking. We cannot guarantee these statements, which
are subject to risks, uncertainties and assumptions that are difficult to
predict. Our actual results may differ materially from those we forecast in
forward-looking statements due to a variety of factors, including those set
forth in the following risk factors, elsewhere in this prospectus and in the
documents we have incorporated by reference. We will not update any
forward-looking statements due to new information, future events or otherwise.
Before investing in the common stock, you should consider carefully the
following factors, as well as the information contained in the rest of this
prospectus and in the documents we incorporate by reference.

WE HAVE INCURRED SUBSTANTIAL LOSSES SINCE WE BEGAN DOING BUSINESS, AND WE
         EXPECT THAT WE WILL CONTINUE TO INCUR LOSSES.

         As of June 30, 1999, our accumulated deficit was $122.4 million. We
first began recognizing product revenue in 1996. For 1996, 1997, 1998 and the
first six months of 1999, we incurred cumulative losses of $76.1 million on
revenues of $30.9 million. Our net losses have increased each year since we
began recognizing revenue. We expect continued losses in 1999 as we market the
AutoPap Primary Screener primarily under a fee-per-use strategy in the United
States, continue product development initiatives and perform additional clinical
studies. We cannot guarantee that our business will ever become profitable.

WE MAY BE UNABLE TO OBTAIN THE ADDITIONAL CAPITAL WE NEED TO FUND OUR
          OPERATIONS.

         We expect negative cash flow from operations to continue at least
through 1999. At June 30, 1999, NeoPath had approximately $9.9 million in cash
and securities available for sale; however, we may require additional funds to
produce AutoPap Systems for our fee-per-use program and cover continuing losses.
We may be unable to obtain adequate funds, whether obtained through financial
markets or from collaborative or other arrangements with corporate partners or
other sources, when we need them, or we may be unable to find adequate funding
on favorable terms, if at all. We intend to seek additional funding through
private debt financing to provide additional resources to support AutoPap
Primary Screener production, but we may be unable to do so. To date, we have had
discussions with various potential lenders. A lender's collateral would be based
primarily on AutoPap Systems placed on multi-year fee-per-use contracts.
SmithKline Beecham Clinical Laboratories is our largest customer; therefore, the
February 1999 announcement that Quest Diagnostics Incorporated agreed to
purchase SmithKline may delay our ability to obtain debt financing.

         We estimate that our existing cash and cash equivalents will meet our
capital requirements through 1999. In the year 2000, we believe our cash
requirement will depend primarily on the placement rate and pricing of
fee-per-use AutoPap Screeners in the United States and outright sales of AutoPap
Screeners in international markets. Fee-per-use placements require us to invest
in initial manufacturing costs to achieve long-term return through monthly
customer payments, whereas AutoPap sales result in cash collection of the full
purchase price under standard payment terms. We cannot guarantee that the
assumptions underlying our estimates will prove to be accurate.

OUR FUTURE FINANCING ARRANGEMENTS MAY DILUTE THE INTERESTS OF OUR
         SHAREHOLDERS OR MAY REQUIRE US TO RELINQUISH IMPORTANT RIGHTS.

         If we raise additional funds by issuing equity securities, existing
shareholders will suffer dilution of their interest in NeoPath. In addition, if
we obtain additional funds through arrangements with collaborative partners, we
may have to relinquish rights to certain of our technologies or potential
products that we would otherwise seek to develop or commercialize ourselves.






                                      -3-
<PAGE>   7

OUR PRODUCTS MAY NOT ACHIEVE MARKET ACCEPTANCE AND WITHOUT MARKET
         ACCEPTANCE OUR REVENUES AND BUSINESS PROSPECTS WILL BE EXTREMELY
         LIMITED.

         Our products may never be commercially successful. NeoPath's growth
depends on market acceptance of the AutoPap Primary Screener by clinical
laboratories, healthcare providers, third-party healthcare payers and patients.
Our success also depends on customers' acceptance of our fee-per-use and sale
programs. Even if our products gain market acceptance, the availability of
reimbursement from third-party healthcare payers such as government and private
insurance plans may limit our revenues.

OUR SALES ARE CONCENTRATED AMONG A RELATIVELY SMALL NUMBER OF CUSTOMERS, AND AS
         CONSOLIDATION CONTINUES IN THE LABORATORY INDUSTRY, THE NUMBER OF
         POTENTIAL CUSTOMERS WILL DECREASE.

         A significant proportion of our sales is concentrated among a
relatively small number of customers, and this likely will be true for the
foreseeable future. For the year ended December 31, 1998, 18% of our revenues
was from SmithKline Beecham Clinical Laboratories in the United States, and 10%
of our revenues was from Chang's Instrument Company Limited in Taiwan. For the
six months ended June 30, 1999, 44% of our revenues was from SmithKline, 17% of
our revenues was from Unilab Corporation and we had no revenues from Chang's.
The loss of SmithKline and Unilab would be materially detrimental to our
business.

         Moreover, due to consolidation in the clinical laboratory industry, we
expect that the number of potential domestic customers for our products will
decrease. These factors increase our dependence on sales to the largest clinical
laboratories and the bargaining power of those potential customers. Our market
research indicates that over 35% of all U.S. Pap smears are screened by the
three largest laboratories, including SmithKline, Quest Diagnostics Incorporated
and Laboratory Corporation of America. Each of these companies operates multiple
laboratory facilities nationwide.

         In February 1999, SmithKline and Quest announced that Quest had agreed
to purchase SmithKline. The combined entity would be the largest clinical
laboratory company in the world. NeoPath's national agreement with SmithKline is
binding on successor organizations, and we believe that the AutoPap Primary
Screeners installed under the SmithKline agreement will continue to generate
revenues in accordance with the underlying agreement. However, additional
AutoPap Primary Screener orders have been delayed as the two laboratories work
through their combined business issues. Future negotiations with SmithKline and
Quest could result in changes to the overall pricing and placement rate under
the existing SmithKline agreement.

IF THIRD-PARTY HEALTH CARE PAYERS RESTRICT REIMBURSEMENT FOR USE OF AUTOPAP
         PRODUCTS, THE MARKET FOR OUR PRODUCTS MAY BECOME EXTREMELY LIMITED.

         Third-party healthcare payers in the United States are increasingly
sensitive to containing healthcare costs and heavily scrutinize new technology
as a primary factor in increased healthcare costs. Third-party payers may
influence the pricing or perceived attractiveness of our products and services
by regulating the maximum amount of reimbursement they provide or by not
providing any reimbursement. Medical community or third-party healthcare payers
may delay acceptance of an automated Pap smear screening or rescreening system
that replaces or supplements current laboratory Pap smear review practices.

         Virtually all of our revenues are dependent on customers who rely on
third party reimbursement. Restrictions on reimbursement may limit the price we
can charge for AutoPap System screening or reduce the demand for AutoPap System
screening. If these payers do not reimburse for the AutoPap System screening, or
provide reimbursement significantly below the amount laboratories charge
patients to perform AutoPap System screening, our product will be less
attractive to our customers and potential customers and potential market and
revenues will be significantly reduced. AutoPap System screening may never
become widely reimbursed, and






                                      -4-
<PAGE>   8

AutoPap reimbursement may not be sufficient to permit us to generate substantial
revenue. Future healthcare legislation or other changes in the administration or
interpretation of government healthcare or third-party reimbursement programs
may also adversely affect our business. Third-party reimbursement also may not
be available for the AutoPap System under foreign reimbursement systems.

IF WE CANNOT OBTAIN AND MAINTAIN REGULATORY CLEARANCE FOR OUR PRODUCTS WE MAY BE
         UNABLE TO SELL ANY OF OUR CURRENT AND FUTURE PRODUCTS IN SOME
         JURISDICTIONS.

         The U.S. government extensively regulates the manufacture and sale of
medical diagnostic devices for commercial use. Government agencies in certain
other countries impose similar requirements. The AutoPap Primary Screener and
AutoPap QC have been cleared for commercialization in the United States and in
Japan, Canada, Australia, New Zealand, The Netherlands, Italy, Hong Kong, Korea,
and Taiwan.

         Governmental regulatory agencies in the United States or elsewhere may
not approve future commercial enhancements to the AutoPap System on a timely
basis, if at all. Even if these agencies clear the enhanced products for sale,
they may not confer the clinical indications we request, or the approval may
contain significant limitations, such as warnings, precautions or
contraindications, requests for postmarket studies, or additional regulatory
requirements. Our regulatory applications may be delayed or rejected based on
changes in regulatory policies or regulations. Regardless of regulatory
approvals, customers may continue to have concerns about the safety and efficacy
of our products. Although the FDA has inspected our manufacturing operations for
compliance with FDA quality systems regulations, we remain subject to ongoing
FDA quality systems regulation and inspection.

OUR LIMITED MARKETING, SALES AND SERVICE EXPERIENCE MAY BE INSUFFICIENT TO
         GENERATE AND MAINTAIN FUTURE SALES OF OUR PRODUCTS.

         We market, sell, service, and support the AutoPap System through a
direct sales force in North America and through independent foreign
distributors. We have limited marketing, sales and service experience, and may
find it difficult to recruit and retain skilled sales, marketing, service or
support personnel or foreign distributors. Our marketing and sales efforts may
not be successful. We provide competitive compensation and benefits, including
stock options, and a professional, challenging environment to retain key
personnel.

WE FACE RISKS INHERENT IN INTERNATIONAL TRANSACTIONS THAT COULD SERIOUSLY
         DIMINISH OUR INTERNATIONAL SALES.

         We rely primarily on third-party distributors to place AutoPap Systems
internationally, and we may encounter difficulties in our dealings with foreign
distributors. International transactions pose a number of risks, including
uncertain sales and collections due to political and economic instability. Any
of these factors may significantly diminish our international sales.

BECAUSE WE HAVE A SOLE OR LIMITED SOURCE OF SUPPLY FOR MANY OF OUR PRODUCT
         COMPONENTS, DISRUPTIONS WITH THESE SUPPLIERS COULD SERIOUSLY IMPEDE OUR
         OPERATIONS.

         We purchase all components for the AutoPap System from outside vendors.
A major component of the AutoPap System, the slide tray motion system, is
supplied by a sole-source vendor, Applied Precision, Inc. In addition, AutoPap
System optics are purchased sole-source from Nikon Corporation, and video
cameras are purchased sole-source from Sony Electronics, Inc. Certain other
components are currently purchased from single-source vendors. Components
provided by additional or replacement suppliers would require some modification
to be used in the AutoPap System. We would be unable to quickly establish
additional or replacement sources of supply for many AutoPap System components.
In addition, we may need to obtain regulatory approval to substitute certain
components. We cannot be sure of obtaining the necessary approvals. If one of
our vendors







                                      -5-
<PAGE>   9

becomes unable to supply acceptable components in a timely manner and in the
quantity required we may need to delay or halt our manufacturing process. Any
delay or cessation of manufacturing could adversely affect our business.

WE MAY BE UNABLE TO ATTAIN OR MAINTAIN REQUIRED COMPLIANCE WITH REGULATIONS
         GOVERNING MANUFACTURING OF MEDICAL DIAGNOSTIC DEVICES, AND OUR FAILURE
         TO DO SO COULD PREVENT US FROM SELLING OUR PRODUCTS.

         Manufacturers of medical diagnostic devices face strict federal
regulations regarding the quality of manufacturing. For example, the FDA
periodically inspects the manufacturing facilities of diagnostic device
manufacturers to determine compliance with regulations. Our current and future
manufacturing and design operations must comply with these and all other
applicable regulations, including regulations imposed by other governments. If
we fail to comply with quality systems regulations we could face civil or
criminal penalties or enforcement proceedings. These proceedings may require us
to recall a product or to stop placing our products in service or selling our
products. Similar results could occur if we violate foreign regulations. We may
not be able to attain or maintain compliance with quality systems requirements.
Any failure to comply with the applicable manufacturing regulations would have a
material adverse effect on our business.

DIRECT COMPETITORS MAY DEVELOP AND MARKET TECHNOLOGIES THAT COMPETE WITH THE
         AUTOPAP SYSTEM, AND THESE PRODUCTS MAY REDUCE THE ATTRACTIVENESS OF OUR
         PRODUCTS OR RENDER OUR PRODUCTS OBSOLETE.

         Competition in the medical device industry is intense. Our competitors
may develop new technologies and products that prove to be more effective than
the AutoPap System in important ways. Furthermore, other companies may purchase
or develop technologies that compete with the AutoPap System or render it
obsolete. These competitors may manufacture, market and sell their products or
services more successfully than us, which could adversely affect our product
sales.

         We believe that the AutoPap System must remain competitive in accuracy
and effectiveness, cost, including both charges by us to the laboratory and the
laboratory's labor and overhead costs, convenience, perception among influential
cytopathologists and laboratories, and processing speed and reliability. The
AutoPap System competes with existing manual methods of screening Pap smears and
with semi-automated systems. To effectively compete, we must keep pace with the
rapid product development and technological change in our industry. The AutoPap
System must demonstrate accuracy and cost effectiveness that equals or exceeds
manual review of Pap smears and the technology that may be offered by our
competitors. We cannot guarantee that the AutoPap System will be competitive in
any of these areas.

         We are aware of two potential direct competitors:

         o  AutoCyte, Inc., which is developing a semi-automated system to
            prepare and analyze liquid-based Pap smears, a potential alternative
            to conventional Pap smears; and

         o  Morphometrix Technologies Inc., which is developing an automated
            system to analyze liquid-based Pap smears

         Neuromedical Systems, Inc., had obtained regulatory approval for a
semi-automated system that rescreens conventional Pap smears and was developing
a semi-automated primary screener. On March 26, 1999, Neuromedical announced
that it had filed a voluntary Chapter 11 petition for bankruptcy.






                                      -6-
<PAGE>   10

OUR PRODUCTS MAY NOT BE INITIALLY COMPATIBLE WITH OTHER TECHNOLOGIES ADOPTED BY
         OUR POTENTIAL CUSTOMERS, WHICH WOULD IMPEDE OUR SALES.

         We face indirect competition from companies that manufacture
liquid-based or monolayer slide preparation systems and devices that automate
various aspects of cytology. On June 18, 1999, AutoCyte announced that it had
received FDA approval for its PREP System, which is a liquid-based preparation
system. In addition, Cytyc Corporation is approved to market its ThinPrep System
that prepares slides for cervical cancer screening using a liquid-based sampling
and preparation technique as a replacement for the conventional Pap smear
method. Because the AutoPap System is not currently approved to process
AutoCyte's PREP or Cytyc's ThinPrep Pap smear, laboratories that choose to use
PREP or ThinPrep are not currently able to fully adopt the AutoPap System.

WE FACE RISKS ASSOCIATED WITH ACQUISITIONS AND MERGERS.

         We may not be successful in integrating the technology rights or
operations from acquisitions and mergers, including NeoPath's pending merger
with AutoCyte. In June 1997, NeoPath acquired the Pathfinder System product
line, for which the resulting intangible assets were written off in the fourth
quarter of 1998. On April 26, 1999, NeoPath and AutoCyte announced an agreement
whereby NeoPath may acquire an undivided interest in the intellectual property
estate of Neuromedical that AutoCyte had agreed to acquire. We have limited
experience with completing and integrating acquisitions. Our business may
include growth by acquisition.

         The AutoCyte transaction and future acquisitions present many risks and
uncertainties generally associated with acquisitions: For example, acquisitions
may divert management's attention from day-to-day operations or disrupt our
ongoing business and operations. This could, among other things, impair our
reputation and our relationships with customers and employees and potentially
cause the loss of our own key employees and customers or those of an acquired
company. Acquisitions may have a negative impact on earnings, as a result of
large one-time write-offs or amortization expenses related to goodwill and other
intangible assets. Acquisitions may require us to issue of equity securities
that may dilute your interest in our company, or cause us to take on additional
debt. We have not yet demonstrated our ability to meet these challenges.

OUR SUCCESS DEPENDS ON A SINGLE PRODUCT LINE, WHICH MAY NEVER BE A COMMERCIAL
         SUCCESS.

         To date, we have concentrated on development of the AutoPap System. We
have performed only limited research on other applications of our core
technology. Accordingly, our success will depend primarily on the successful
development and marketing of the AutoPap System to generate revenues. The
AutoPap System may never be a commercial success.

FUTURE PRODUCT LIABILITY CLAIMS MAY STRAIN OUR FINANCIAL RESOURCES AND HARM OUR
         BUSINESS REPUTATION.

         The commercial screening of Pap smears has generated significant
malpractice litigation. As a result, we face product liability, errors and
omissions or other claims if our products are alleged to have caused a
false-negative diagnosis. Although we have product liability insurance, it will
become increasingly difficult for us to obtain and maintain reasonable product
liability coverage. Our current product liability coverage is limited to $25
million. Substantial increases in insurance premium costs often make coverage
economically impractical. We may not be able to obtain adequate product
liability insurance at a reasonable cost. Thus, product liability claims may
strain our financial resources and harm our business reputation.







                                      -7-
<PAGE>   11

OUR PATENTS, TRADE SECRETS AND CONFIDENTIALITY AGREEMENTS MAY NOT ADEQUATELY
         PROTECT OUR PROPRIETARY TECHNOLOGY, RIGHTS AND KNOW-HOW, WHICH MAY
         REDUCE THE VALUE OF THE TECHNOLOGIES UPON WHICH OUR BUSINESS DEPENDS.

         We rely on a combination of patents, trade secrets and confidentiality
agreements to protect our proprietary technology, rights and know-how. We hold 7
foreign patents, 58 U.S. patents (issued or allowed), and have 22 additional
U.S. patents pending. NeoPath's patents expire in 2012-2018. Pending patent
applications may not ultimately issue as patents or, if patents do issue, may
not be sufficiently broad to protect our proprietary rights. Competitors may
challenge or circumvent our patents or pending applications. Our patents may
never provide us with any competitive advantages. We pursue selected
international patents only in key markets. In certain foreign countries,
protection of our patent and other intellectual property may be unavailable or
very limited. Given our focused strategy internationally, we have not
experienced significant inability to obtain sought-after intellectual property.
However, such protection may be unavailable or very limited in future markets
that we have not yet targeted. Our confidentiality agreements with employees and
other parties may not protect the confidentiality of our trade secrets and
proprietary information or provide meaningful protection for our confidential
information. In addition, our competitors could independently develop our trade
secrets or proprietary information.

THIRD-PARTY CLAIMS OF INFRINGEMENT MAY STRAIN OUR FINANCIAL RESOURCES AND MAY
         LIMIT OUR ABILITY TO USE THE TECHNOLOGIES ON WHICH OUR BUSINESS
         DEPENDS.

         Our business is based on highly complex visual intelligence technology.
We may face third party claims of infringement with regard to our products and
technology. Defending these claims may strain our financial resources, and the
resolution of these claims may limit our ability to use the technologies on
which our business depends.


         For example, on July 15, 1996, Neuromedical filed a lawsuit against
NeoPath in the United States District Court for the Southern District of New
York. The complaint alleged patent infringement, unfair competition, false
advertising, and related claims and requested monetary damages and injunctive
relief. On September 5, 1996, we filed our answer and counter claims. In May
1998, a judge in the United States District Court for the Southern District of
New York denied Neuromedical's motion for a preliminary injunction against us.
The parties agreed to dismiss their claims and counterclaims on all but the
patent issues, and Neuromedical accordingly served an amended complaint on July
27, 1998 asserting only patent infringement claims. Virtually all of our
domestic revenues, which represented 81% of total revenues in 1998, are derived
from products that incorporate technology covered by this patent. We believe
NeoPath has a strong position in this action, and we will defend against these
claims vigorously. On March 26, 1999, Neuromedical announced that it had filed a
voluntary chapter 11 petition for bankruptcy. On April 6, 1999, the court
removed the case from its active docket pending further developments in
Neuromedical's bankruptcy proceedings.


         On March 31, 1997, NeoPath filed a patent infringement lawsuit against
Neuromedical in the United States District Court for the Western District of
Washington. Our complaint alleges patent infringement and seeks permanent
injunctions against Neuromedical. In March and April 1998 this lawsuit was
amended, and NeoPath filed an additional related patent lawsuit against
Neuromedical. Neuromedical filed a motion for summary judgment, which the court
denied in April 1998. In October 1998, Neuromedical filed another motion for
summary judgment that the court denied. By court order on March 30, 1999,
proceedings have been stayed pending resolution of Neuromedical's bankruptcy
proceedings. Furthermore, the court ordered that these cases be removed from the
court's active caseload.


         We have entered into an intellectual property acquisition agreement
with AutoCyte that provides that the patent infringement litigation between
NeoPath and Neuromedical will be terminated, but our agreement with







                                      -8-
<PAGE>   12


AutoCyte is subject to several conditions that are beyond our control.
Therefore, we cannot predict the outcome of this patent litigation. An
unfavorable resolution of any of these issues could materially adversely affect
our business. See "Other Recent Events -- Agreement to acquire technology
rights."


INTENSE COMPETITION FOR THE SERVICES OF OUR KEY PERSONNEL COULD CAUSE THEM TO
         LEAVE NEOPATH.

         We depend heavily on the principal members of our management and
scientific staff. The loss of their services might impede achievement of our
strategic objectives or research and development. Our success depends on our
ability to retain key employees and to attract additional qualified employees.
Competition for highly skilled scientific and management personnel is intense,
particularly in the Western Washington region, where such resources are scarce
relative to the needs of a growing high technology business sector. The failure
to recruit such personnel or the loss of existing personnel could adversely
affect our business. We do not carry key person life insurance on our executives
or other key personnel.

OUR STOCK PRICE HAS BEEN HIGHLY VOLATILE, AND WE EXPECT THIS VOLATILITY TO
         CONTINUE, WHICH COULD RESULT IN LOWER STOCK PRICES FOR EXTENDED
         PERIODS.

         The market price of our common stock has been, and may continue to be,
highly volatile. Our stock trades on the Nasdaq National Market. Since the
beginning of 1998, our stock has traded as high as $18.19 and as low as $3.00
per share. In addition to changes in general market and economic conditions, any
of the factors addressed in this Risk Factors section may significantly
influence the future price of the common stock you purchase in this offering.
The market price of our common stock could fall, and our stock price may remain
low for extended periods.

OUR QUARTERLY RESULTS MAY FLUCTUATE IN FUTURE PERIODS, AND THESE FLUCTUATIONS
         MAY CAUSE OUR STOCK PRICE TO DECLINE.

         We expect our operating results to fluctuate significantly from quarter
to quarter in the future. These fluctuations may cause our results to be below
analysts' and investors' expectations, causing the market price of our common
stock to decline.


         For instance, our revenues for the quarter ended June 30, 1999
consisted of $2.1 million of fee-per-use and service fees and $0.8 million of
AutoPap product sales. Revenues in the comparable 1998 quarter included $0.9
million of fee-per-use and service fees, $3.3 million of AutoPap System product
sales, and $0.1 million of Pathfinder product sales. Pathfinder product sales
were not significant in the three months ended June 30, 1999. NeoPath's
fee-per-use and service revenues increased 145 percent from the second quarter
of 1998, while AutoPap product sales decreased 77 percent in the same period.
International revenues accounted for 14 percent of total revenues in the second
quarter of 1999, compared to 31 percent in the comparable period in 1998.

         The increase in fee-per-use and service revenues in the three-month
period ended June 30, 1999 was attributable to a greater number of AutoPap
Systems processing slides under fee-per-use contracts in 1999 as compared to
1998, as well as improved per-slide pricing in the current year. The decrease in
AutoPap product sales from the prior period was primarily the result of having
fewer international AutoPap System sales in 1999 compared to 1998. In the second
quarter of 1998, our sale transactions included four AutoPap Systems in Taiwan;
this contrasts with one international system sale in the second quarter of 1999.
In addition, we had no domestic AutoPap System sales in the latter period. The
decrease in product sales demonstrates a shift in our operating revenues from
outright AutoPap sales to a mix of outright sales, primarily in international
markets, and fee-per-use contracts for AutoPap placements in the U.S. To date,
our AutoPap System placements have consisted primarily of fee-per-use contracts
in the U.S. and sale contracts internationally. AutoPap product sales may
generate significant revenues in future quarters, but we cannot predict product
sale revenues, which may not be realized. Quarterly net








                                      -9-
<PAGE>   13


losses have ranged from $8.1 million in the quarter ended December 31, 1998 to
$3.5 million in the quarter ended June 30, 1998.


         A number of factors have caused and may continue to cause these
fluctuations. For instance, fee-per-use contracts result in lower short-term
revenues than AutoPap product sales. Total revenues will be lower in quarters in
which there are few or no AutoPap product sales compared to quarters with
greater number of AutoPap product sales. Thus the timing and mix of fee-per-use
and sale revenues may cause substantial fluctuations in our total revenues from
quarter to quarter. Though we expect recurring fee-per-use revenues to grow,
AutoPap product sale patterns may continue to cause significant fluctuations in
revenues. Delays in the timing of medical reimbursement approvals may cause
revenues to decline in particular periods. Similarly, if our competitors
introduce new products we may experience unexpected delays in AutoPap
placements. For any of these reasons, our revenues may fall short of our
projections or analysts' expectations in particular periods.

         In addition, our quarterly results may fluctuate significantly due to
the timing of our expenditures. We may need to spend relatively large sums in a
particular quarter to pay for clinical studies and regulatory submissions or to
fund research and development projects. In most cases, these expenditures will
not be immediately offset by increased revenues from the products supported by
these expenditures. Our results in quarters in which we make such expenditures
may not compare favorably to our results in other quarters.

THE YEAR 2000 PROBLEM MAY CAUSE DISRUPTION OF OUR OPERATIONS BECAUSE WE CANNOT
         CONTROL COMPLIANCE BY OUR SUPPLIERS AND SUBCONTRACTORS, AND BECAUSE WE
         HAVE NO CONTINGENCY PLANS.

         We need to modify or replace certain portions of our internal systems
and product software and certain hardware so that those systems will properly
recognize dates beyond December 31, 1999. However, we have identified no
significant Year 2000 issues that cannot be resolved through software or
hardware upgrades that are currently available or expected to be available soon.
We are using our existing internal resources to reprogram or replace
noncompliant internal systems and product hardware and software. However, if
such modifications and replacements are not made, or are not completed in a
timely manner, the Year 2000 issue could result in system errors or failures and
could significantly disrupt Neopath's and its customers' operations.

         We have asked our significant suppliers and subcontractors about their
Year 2000 compliance status. To date, we are not aware of any external agent
with Year 2000 problems that would materially affect our results of operations,
liquidity, or capital resources. However, we have no means of ensuring that
these agents will be Year 2000 ready. If our suppliers and subcontractors do not
complete their Year 2000 resolution process in a timely fashion we could face
significant business interruptions that could harm our business. We cannot
accurately predict the effect of non-compliance by external agents.

         The Company currently has no contingency plans in place in the event it
does not complete all phases of the Year 2000 program, including the possibility
that its external agents are not Year 2000 ready. If we or others do not make
necessary modifications and conversions, or do not complete them on time, the
Year 2000 Issue could disrupt NeoPath's operations and materially affect its
business, financial condition, and results of operations.







                                      -10-
<PAGE>   14



                               OTHER RECENT EVENTS


AGREEMENT TO ACQUIRE TECHNOLOGY RIGHTS

         On March 26, 1999, AutoCyte, Inc. announced an agreement to purchase
certain Neuromedical, Inc. technology, including patent rights, for $4.0 million
in cash and 1.4 million shares of AutoCyte common stock. On April 26, 1999,
NeoPath and AutoCyte announced an agreement whereby NeoPath may acquire an
undivided interest in the intellectual property estate of Neuromedical that
AutoCyte had agreed to acquire. On May 18, 1999, AutoCyte announced that it had
completed its acquisition of the Neuromedical technology. Subject to certain
conditions, NeoPath will pay AutoCyte $2.2 million in cash and issue AutoCyte
1.2 million shares of NeoPath common stock at the later of the transaction
closing date or September 1, 1999. However, we do not anticipate that this
transaction will be concluded if the merger with AutoCyte is completed.

PRIVATE EQUITY TRANSACTION

         On February 9, 1999, we completed a $14.5 million private equity
transaction in which we issued 2.9 million shares of common stock to investors
at a price of $5.00 per share. On February 9, 1999, the last reported sale price
of the common stock on Nasdaq was $5.125. We have filed this shelf registration
statement on Form S-3 to allow resale of these shares. We have agreed to use our
best efforts to keep this registration statement effective for two years. The
transaction agreement specified that the purchase price to the investors would
be reduced by 2 percent if this registration statement were not declared
effective within 120 days of the transaction closing. As a result, NeoPath
recognized a liability of $290,000 as of June 30, 1999. In connection with the
financing, we issued to Invemed Associates, Inc., an investment banking firm,
five-year warrants to purchase 100,000 shares of common stock at an exercise
price of $5.89 per share. The proceeds of the private placement have been, and
will be, used to fund our operating cash requirements.

WRITE-OFF OF PATHFINDER INTANGIBLE ASSETS

         In the quarter ended December 31, 1998, we wrote off $3.1 million of
intangible assets related to our Pathfinder System product line. The write-off
did not involve any cash expenditure. NeoPath acquired the Pathfinder System
product line from CompuCyte Corporation in June 1997 for a total purchase price
of $4.6 million, including transaction-related expenses. As a result of the
purchase, we recognized $4.3 million in intangible assets that were to be
amortized over five years.

         The intangible assets included the following:

<TABLE>
<CAPTION>
                                      JUNE 1997               DECEMBER 1998
                                  INITIAL ALLOCATION     WRITE-OFF OF REMAINING
                                  OF PURCHASE PRICE          NET BOOK VALUE
                                  ------------------     ----------------------
<S>                                    <C>                       <C>
Patents                                $2,000,000                $1,400,000
Trademark                                 100,000                    70,000
Copyright                                 200,000                   140,000
Non-compete agreement                     400,000                   280,000
Goodwill                                1,609,195                 1,194,289
                                      -----------               -----------
         Total                         $4,309,195                $3,084,289
                                       ==========                ==========
</TABLE>

         At the time of the acquisition, our financial projections indicated
that PathFinder would generate significant future revenues. We based our initial
PathFinder revenue projections on information available at the time, making
numerous assumptions about likely domestic and international market acceptance
rates, the robustness of the









                                      -11-
<PAGE>   15


PathFinder technology, and the brief selling history recorded by CompuCyte.
Based on these factors, we also expected significant undiscounted positive cash
flows. However, actual revenues and cash flows have been significantly below our
original expectations. PathFinder product sales accounted for 3 percent of total
revenues in 1998, and we no longer offer the PathFinder System.

         We noted the following indications of impairment from PathFinder, in
the fourth quarter of 1998:

         o  continued low revenue levels and operating losses from PathFinder,
            despite initiatives to train sales personnel on PathFinder
            demonstrations and sales commission incentives;

         o  a product assessment completed in the fourth quarter of 1998 that
            demonstrated significant technology changes would be necessary to
            make PathFinder commercially viable and acceptable to a broad base
            of laboratory customers; and

         o  sales forecasts prepared in the fourth quarter of 1998 that
            predicted continuing product line losses and negative cash flows.

         Using our revised PathFinder sales forecast figures, we prepared a cash
flow analysis and determined that future PathFinder undiscounted cash flows
would likely be negative. In accordance with required accounting practices, we
compared the carrying value of the PathFinder intangible assets to expected
future discounted cash flows applicable to the PathFinder product and, as a
result of the analysis, wrote off the entire $3.1 million remaining balance of
intangible assets.


                           FORWARD-LOOKING INFORMATION

         This prospectus includes "forward-looking statements" within the
meaning of the Private Securities Litigation Reform Act of 1995. The Act
provides a "safe harbor" for forward-looking statements to encourage companies
to provide prospective information about themselves so long as they identify
these statement as forward-looking and provide meaningful cautionary statements
identifying important factors that could cause actual results to differ from the
projected results. All statements other than statements of historical fact we
make in this Prospectus or in any document incorporated by reference are
forward-looking. In particular, the statements herein regarding industry
prospects and our future results of operations or financial position are
forward-looking statements. Forward-looking statements reflect our current
expectations and are inherently uncertain. Our actual results may differ
significantly from our expectations. The section entitled "Risk Factors"
describes some, but not all, of the factors that could cause these differences.


                         HOW TO OBTAIN MORE INFORMATION

         We file reports, proxy statements and other information with the
Securities and Exchange Commission. You may read any document we file at the
SEC's public reference rooms in Washington, D.C., Chicago, Illinois and New
York, New York. Please call the SEC toll free at 1-800-SEC-0330 for information
about its public reference rooms. You may also read our filings at the SEC's web
site at http://www.sec.gov.

         We have filed with the SEC a registration statement on Form S-3 under
the Securities Act. This prospectus does not contain all of the information in
the registration statement. We have omitted certain parts of the registration
statement, as permitted by the rules and regulations of the SEC. You may inspect
and copy the registration statement, including exhibits, at the SEC's public
reference facilities or web site. Our statements in this prospectus about the
contents of any contract or other document are not necessarily complete. You
should refer to the copy of each contract or other document we have filed as an
exhibit to the registration statement for complete information.









                                      -12-
<PAGE>   16

         The SEC allows us to "incorporate by reference" into this prospectus
the information we file with it. This means that we can disclose important
information to you by referring you to those documents. This information we
incorporate by reference is considered a part of this prospectus, and later
information we file with the SEC will automatically update and supersede this
information. We incorporate by reference the documents listed below and any
future filings we make with the SEC under Sections 13(a), 13(c), 14 and 15(d) of
the Securities Exchange Act of 1934 until this offering is completed:

         1.  NeoPath's Annual Report on Form 10-K for the year ended December
             31, 1998;

         2.  NeoPath's Quarterly Reports on Form 10-Q for the quarters ended
             March 31, 1999 and June 30, 1999;

         3.  NeoPath's Report on Form 8-K filed June 23, 1999;

         4.  The description of the common stock in NeoPath's Registration
             Statement on Form 8-A effective as of November 30, 1994, including
             any amendment or report filed to update the description; and

         5.  All other documents filed by NeoPath pursuant to Section 13(a),
             13(c), 14 or 15(d) of the Exchange Act after the date of this
             prospectus and prior to the termination of this offering.

         You may obtain copies of these documents, without exhibits, free of
charge by contacting NeoPath's corporate secretary at our principal offices,
which are located at 8271 - 154th Avenue NE, Redmond, Washington 98052,
telephone number (425) 869-7284. You may visit our website at www.neopath.com.

         You should rely only on the information incorporated by reference or
provided in this prospectus or any prospectus supplement. We have not authorized
anyone else to provide you with different information. The selling shareholders
are not making an offer of these securities in any state where the offer is not
permitted. You should not assume that the information in this prospectus or any
prospectus supplement is accurate as of any date other than the date on the
front of the document.

         AutoCyte also files reports, proxy statement and other information with
the Commission. We encourage you to learn more about AutoCyte by reading these
documents. You may read any document AutoCyte files at the SEC's public
reference rooms in Washington, D.C., Chicago, Illinois and New York, New York.
Please call the SEC toll free at 1-800-SEC-0330 for information about its public
reference rooms. You may also read their filings at the SEC's web site at
http://www.sec.gov.











                                      -13-
<PAGE>   17

                              SELLING SHAREHOLDERS

         The following table presents information regarding the selling
shareholders and the number of shares they may offer by this prospectus.

<TABLE>
<CAPTION>
                                                                                            SHARES BENEFICIALLY OWNED
                                                               SHARES THAT MAY BE SOLD            AFTER OFFERING
                                                              -------------------------   ----------------------------
                                                  SHARES
                                               BENEFICIALLY               PERCENTAGE OF                  PERCENTAGE OF
                                               OWNED PRIOR                 COMMON STOCK                   COMMON STOCK
            NAME OF SHAREHOLDER                TO OFFERING      AMOUNT     OUTSTANDING      AMOUNT        OUTSTANDING
            -------------------                ------------   ---------   -------------   ---------      -------------
<S>                                             <C>           <C>               <C>         <C>                <C>
The Kaufmann Fund, Inc.                         2,071,000     1,821,000         10.5%       250,000            1.4%

Capital  Research and Management  Company on
behalf of SmallCap World Fund, Inc.             1,121,400       500,000          2.9%       621,400            3.6%

The Jenifer Altman Foundation                      21,000         7,000             *        14,000               *

Alza Corporation Retirement Plan                   21,000         6,000             *        15,000               *

Dean Witter Foundation                             21,000         6,000             *        15,000               *

The Ferris Hamilton Family Trust                   15,000         5,000             *        10,000               *

John J. & Catherine H. Kayola                       4,000         4,000             *            --               *

Arthur D. Little Employee Investment Plan         160,000        60,000             *       100,000               *

The Magee/Bernhard LLC                             43,000        18,000             *        25,000               *

The Meehan Investment Partnership I, L.P.          16,000         4,000             *        12,000               *

Margaret M. Legacy                                 21,000         6,000             *        15,000               *

NFIB Employee Pension Trust                        32,000        12,000             *        20,000               *

NFIB Corporate Account                             28,000        15,000             *        13,000               *

Norwalk Employees' Pension Plan                    72,000        12,000             *        60,000               *

Public Employee Retirement System of Idaho        270,000       120,000             *       150,000               *

Roanoke College                                    26,000         6,000             *        20,000               *

The A & JS Family LLC                              27,000        11,000             *        16,000               *

City of Stamford Firemen's Pension Fund            53,000        18,000             *        35,000               *

State of Oregon PERS/ZCG                          840,000       240,000          1.4%       600,000            3.5%

Van Loben Sels Foundation                          21,000         5,000             *        16,000               *

The A & SW Family LLC                              27,700        12,000             *        15,700               *

Wells Family LLC                                   31,000         6,000             *        25,000               *

Wolfson Investment Partners LP                     26,000         6,000             *        20,000               *
                                               ----------     ---------       -------      --------         -------
                                                4,968,100     2,900,000         16.7%     2,068,100           11.9%
</TABLE>

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










                                      -14-
<PAGE>   18

         None of the selling shareholders has had any material relationship with
NeoPath or its affiliates within the past three years. The selling shareholders
purchased all of the shares from NeoPath in a private transaction on February 9,
1999. All of the shares were "restricted securities" under the Securities Act
prior to this registration.

         The selling shareholders have represented to us that they purchased the
shares for their own account for investment only and not with a view towards
selling or distributing them, except pursuant to sales registered under the
Securities Act or exemptions. NeoPath agreed with the selling shareholders to
file the registration statement to register the resale of the shares. NeoPath
agreed to prepare and file all necessary amendments and supplements to the
registration statement to keep it effective until the earlier of (1) February 9,
2001 and (2) the date on which the selling shareholders have sold all the
shares.


                              PLAN OF DISTRIBUTION

         We are registering the shares on behalf of the selling shareholders and
their successors (including donees and pledgees, who may sell shares they
receive from the selling shareholders after the date of this prospectus). The
selling shareholders or their successors may sell all of the shares from time to
time in transactions in the over-the-counter market through Nasdaq, or on one or
more other securities markets and exchanges, in privately negotiated
transactions or through writing options on the shares. They may sell the shares
at fixed prices that may change, at market prices prevailing at the time of
sale, at prices relating to prevailing market prices or at negotiated prices.
The selling shareholders may sell the shares to or through broker-dealers. These
broker-dealers may receive compensation in the form of discounts, concessions or
commissions from the selling shareholders and/or the purchasers.

         The selling shareholders have advised us that they have not entered
into any agreements, understandings or arrangements for the sale of the shares
with any underwriters or broker-dealers and that no underwriter or coordinating
broker is now acting in connection with the proposed sale of shares.

         NeoPath will not receive any proceeds from the sale of the shares by
the selling shareholders. NeoPath may suspend use of this prospectus under
certain circumstances.

         The selling shareholders and broker-dealers who assist in the sale of
the shares may be "underwriters" within the meaning of Section 2(11) of the
Securities Act. Any commissions or profit they earn on any resale of the shares
may be underwriting discounts and commissions under the Securities Act. Selling
shareholders who are "underwriters" within the meaning of Section 2(11) of the
Securities Act will be subject to the prospectus delivery requirements of the
Securities Act. We have informed the selling shareholders that the
anti-manipulative provisions of Regulation M of the Exchange Act may restrict
their sales in the market.

         NeoPath will pay all expenses, other than selling commissions and fees
and stock transfer taxes, of the registration and sale of the shares. NeoPath
also has agreed to indemnify the selling shareholders and broker-dealers who
assist in the sale of the shares against certain liabilities, including
liabilities under the Securities Act. The selling shareholders may indemnify any
agent, dealer or broker-dealer that assists them in selling the shares against
certain liabilities, including liabilities arising under the Securities Act.

         We cannot guarantee that the selling shareholders will sell any or all
of the shares.









                                      -15-
<PAGE>   19

                            VALIDITY OF COMMON STOCK

         Perkins Coie LLP, Seattle, Washington, will provide NeoPath with an
opinion as to legal matters in connection with the common stock offered by this
prospectus.


                                     EXPERTS

         The financial statements of NeoPath, Inc. incorporated by reference in
NeoPath, Inc.'s Annual Report (Form 10-K) for the year ended December 31, 1998,
have been audited by Ernst & Young LLP, independent auditors, as set forth in
their report thereon incorporated by reference therein and incorporated herein
by reference. Such financial statements are incorporated herein by reference in
reliance upon such report given on the authority of such firm as experts in
accounting and auditing.



























                                      -16-
<PAGE>   20


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


     WE HAVE NOT AUTHORIZED ANY PERSON TO GIVE YOU ANY INFORMATION OR TO MAKE
ANY REPRESENTATIONS OTHER THAN THOSE CONTAINED IN THIS PROSPECTUS. YOU SHOULD
NOT RELY ON ANY INFORMATION OR REPRESENTATIONS OTHER THAN THIS PROSPECTUS. THIS
PROSPECTUS IS NOT AN OFFER TO SELL OR A SOLICITATION OF AN OFFER TO BUY ANY
SECURITIES OTHER THAN THE COMMON STOCK. IT IS NOT AN OFFER TO SELL OR A
SOLICITATION OF AN OFFER TO BUY SECURITIES IF THE OFFER OR SOLICITATION WOULD BE
UNLAWFUL. THE AFFAIRS OF NEOPATH MAY HAVE CHANGED SINCE THE DATE OF THIS
PROSPECTUS. YOU SHOULD NOT ASSUME THAT THE INFORMATION IN THIS PROSPECTUS IS
CORRECT AT ANY TIME SUBSEQUENT TO ITS DATE.


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







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







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










                                2,900,000 SHARES





                                  NEOPATH, INC.

                                  COMMON STOCK






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

                                   PROSPECTUS

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



















                                AUGUST ____, 1999

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






<PAGE>   21

                                     PART II

                     INFORMATION NOT REQUIRED IN PROSPECTUS


ITEM 14.  OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION

         The following table sets forth the costs and expenses, other than
underwriting discounts payable, by the registrant in connection with the sale of
common stock being registered. All amounts are estimates except the SEC
registration fee and the Nasdaq National Market additional listing fee.

<TABLE>
<S>                                                                 <C>
         SEC registration fee....................................   $   4,233
         Nasdaq National Market listing fee .....................      17,500
         Legal fees and expenses ................................      35,000
         Accounting fees and expenses ...........................      25,000
                                                                    ---------
              Total..............................................   $  81,733
                                                                    =========
</TABLE>

ITEM 15.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Sections 23B.08.500 through 23B.08.600 of the Washington Business
Corporation Act authorize a court to award, or a corporation's board of
directors to grant, indemnification to directors and officers on terms
sufficiently broad to permit indemnification under certain circumstances for
liabilities arising under the Securities Act of 1933, as amended (the
"Securities Act"). Section 10 of the registrant's Bylaws provides for
indemnification of the registrant's directors, officers, employees and agents to
the maximum extent permitted by Washington law.

         Section 23B.08.320 of the Washington Business Corporation Act
authorizes a corporation to limit a director's liability to the corporation or
its shareholders for monetary damages for acts or omissions as a director,
except in certain circumstances involving intentional misconduct, knowing
violations of law or illegal corporate loans or distributions, or any
transaction from which the director personally receives a benefit in money,
property or services to which the director is not legally entitled. Article 8 of
the registrant's Articles of Incorporation contains provisions implementing, to
the fullest extent permitted by Washington law, such limitations on a director's
liability to the registrant and its shareholders.

         The Registrant also has entered into indemnification agreements under
which it has agreed, among other things, to indemnify its directors and officers
against certain liabilities.









                                      II-1
<PAGE>   22

ITEM 16.  EXHIBITS

          5.1*      Opinion of Perkins Coie LLP, counsel to the registrant,
                    regarding the legality of the Common Stock

         23.1       Consent of Ernst & Young LLP, Independent Auditors

         23.2*      Consent of Perkins Coie LLP (contained in Exhibit 5.1)

         24.1*      Power of Attorney (contained on signature page)

         *          Filed previously on February 12, 1999 (File No. 333-72261).

ITEM 17.  UNDERTAKINGS

         A.       The undersigned Registrant hereby undertakes:

                  (1) To file, during any period in which offers or sales are
being made, a post-effective amendment to this Registration Statement (i) to
include any prospectus required by Section 10(a)(3) of the Securities Act of
1933; and (ii) to reflect in the prospectus any facts or events arising after
the effective date of the registration statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in the registration
statement. Notwithstanding the foregoing, any increase or decrease in volume of
securities offered (if the total dollar value of securities offered would not
exceed that which was registered) and any deviation from the low or high end of
the estimated maximum offering range may be reflected in the form of prospectus
filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the
changes in volume and price represent no more than 20 percent change in the
maximum aggregate offering price set forth in the "Calculation of Registration
Fee" table in the effective registration statement;

                  (2) That, for the purpose of determining any liability under
the Securities Act of 1933, each such post-effective amendment shall be deemed
to be a new registration statement relating to the securities offered therein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof; and

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

         B.       The undersigned Registrant hereby undertakes that, for
purposes of determining any 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 herein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

         C.       Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Registrant pursuant to the foregoing provisions, or otherwise,
the Registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the Securities Act and is, therefore, unenforceable. In the event that a
claim for indemnification against such liabilities (other than







                                      II-2
<PAGE>   23

the payment by the Registrant of expenses incurred or paid by a director,
officer or controlling person of the Registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer or controlling
person in connection with the securities being registered, the Registrant will,
unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question of 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.

         D.       The undersigned Registrant hereby undertakes that:

                  (1) For purposes of determining any liability under the
Securities Act of 1933, 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.

                  (2) For the purpose of determining any liability under the
Securities Act of 1933, 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-3

<PAGE>   24

                                   SIGNATURES



         Pursuant to the requirements of the Securities Act of 1933, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-3 and has duly caused this Amendment
No. 4 to the Registration Statement to be signed on its behalf by the
undersigned, thereunder duly authorized, in the City of Redmond, State of
Washington, on the 24th day of August, 1999.




                           NeoPath, Inc.



                           /s/ ROBERT C. BATEMAN
                           -------------------------------------------------
                           By: Robert C. Bateman
                               Vice President, Finance, Chief Financial Officer,
                               Treasurer and Secretary



         Pursuant to the requirements of the Securities Act of 1933, this
Amendment No. 4 to the Registration Statement has been signed by the following
persons in the capacities indicated below on the 24th day of August, 1999.


<TABLE>
<CAPTION>
                       SIGNATURE                                                       TITLE
                       ---------                                                       -----

<S>                                                       <C>
                /s/ RONALD R. BROMFIELD                   President, Chief Executive Officer, and Director
--------------------------------------------------------  (Principal Executive Officer)
                  Ronald R. Bromfield


                           *                              Chairman of the Board
--------------------------------------------------------
                     Alan C. Nelson


                 /s/ ROBERT C. BATEMAN                    Vice President, Finance, Chief Financial Officer,
--------------------------------------------------------  Treasurer and Secretary (Principal Financial and
                   Robert C. Bateman                      Accounting Officer)


                           *                              Director
--------------------------------------------------------
                  Thomas A. Bonfiglio


                           *                              Director
--------------------------------------------------------
                   Cristina H. Kepner


                           *                              Director
--------------------------------------------------------
                     Walter L. Robb


                           *                              Director
--------------------------------------------------------
                    William L. Scott
</TABLE>










                                      II-4
<PAGE>   25

<TABLE>
<S>                                                       <C>
                           *                              Director
--------------------------------------------------------
                   David A. Thompson


              * By: /s/ ROBERT C. BATEMAN                 Attorney-In-Fact
--------------------------------------------------------
                   Robert C. Bateman
</TABLE>


































                                      II-5

<PAGE>   26


                                  EXHIBIT INDEX



<TABLE>
<CAPTION>
EXHIBIT
NUMBER
-------
<S>       <C>
  5.1*    Opinion of Perkins Coie LLP, counsel to the registrant, regarding the
          legality of the Common Stock

 23.1     Consent of Ernst & Young LLP, Independent Auditors

 23.2*    Consent of Perkins Coie LLP (contained in Exhibit 5.1)

 24.1*    Power of Attorney (contained on signature page)

 *        Filed previously on February 12, 1999 (File No. 333-72261).
</TABLE>