UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C.  20549
                       ----------------------------------

                                   FORM 10-K

            (Mark One)
            [X]  ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                 SECURITIES EXCHANGE ACT OF 1934 
                 For the Fiscal Year Ended December 31, 1998

                                        OR

            [ ]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF
                 THE SECURITIES EXCHANGE ACT OF 1934 
                 For the transition period from _________ to ________

            Commission File No. 1-12714

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

                       MINNESOTA                            41-0955959
            (State or other jurisdiction of             (I.R.S. Employer
             incorporation or organization)              Identification No.)

                              5951 CLEARWATER DRIVE
                           MINNETONKA, MINNESOTA  55343
                     (Address of principal executive offices)
                                   (Zip Code)

                                 (612) 933-2277
                         (Registrant's telephone number)

            Securities registered pursuant to Section 12(b) of the Act:

            Common Shares, par value             New York Stock Exchange
            $0.01 per share                  (Name of each exchange on which
             (Title of each class)            registered)

            Securities registered pursuant to Section 12(g) of the Act:

                                       None.

            Indicate by check mark whether the registrant (1) has filed all
            reports required to be filed by Section 13 or 15(d) of the
            Securities Exchange Act of 1934 during the preceding 12 months
            (or for such shorter period that the registrant was required to
            file such reports), and (2) has been subject to such filing
            requirements for the past 90 days.

                              Yes  __X__     No ____

            Indicate by check mark if disclosure of delinquent filers
            pursuant to Item 405 of Regulation S-K is not contained herein,
            and will not be contained, to the best of Registrant's
            knowledge, in definitive proxy or information statements
            incorporated by reference in Part III of this Form 10-K or
            or any amendment to this form 10-K.   [X].

            As of March 17, 1999, 14,008,163 Common Shares were
            outstanding.  The aggregate market value of the Common
            Shares held by non-affiliates of the Registrant on such date
            (based upon the closing price of such shares on the New York
            Stock Exchange on March 17, 1999) was $112,065,304.


                      DOCUMENTS INCORPORATED BY REFERENCE

            Portions of the Annual Report to Shareholders for the
            fiscal year ended December 31, 1998 (the "Annual Report to
            Shareholders"), are incorporated by reference into Parts II
            and IV.  Portions of the definitive Proxy Statement for the
            Annual Meeting of Shareholders to be held on May 12, 1999
            (the "Proxy Statement"), and to be filed within 120 days
            after the Registrant's fiscal year ended December 31, 1998,
            are incorporated by reference into Part III.


                                     PART I

            ITEM 1.  BUSINESS

            The following discussion contains certain information
            and other forward-looking statements that involve a number
            of risks and uncertainties.  The actual results of Osmonics
            could differ materially from the Company's historical
            results of operations and those discussed in the forward-
            looking statements.  See "Certain Factors" and other
            portions of this Form 10-K for discussion of some of these
            risks and uncertainties.

            Osmonics, Inc., founded in 1969, and its wholly-owned
            subsidiaries (the "Company") design, manufacture and market
            a wide range of products used in the filtration, separation
            and processing of fluids.  The Company classifies its
            products into two segments, namely Consumables and Equipment.

            Filtration processes cover a broad spectrum ranging
            from those which separate discrete molecules and ions to
            those which separate particles visible to the naked eye. 
            Historically, the Company specialized in Consumables and
            Equipment utilizing crossflow filtration processes designed
            to separate particles in the molecular range.  Through
            acquisitions and internal product developments, the Company
            now manufactures a full line of filtration Consumables and
            Equipment.


            DEVELOPMENT OF BUSINESS

            In addition to developing the Company's product line
            through internal research and development, the Company has
            expanded its business through a series of acquisitions. 
            Recent primary acquisitions include: 

            AUTOTROL - In October 1993, the Company acquired Autotrol
            Corporation, founded in 1962, a manufacturer of
            controllers for water softening and filtration equipment.
            In addition, Autotrol manufactures other fluid control
            and measuring devices such as a totalizing flow meter and
            dosing system to assure proper treatment of cooling tower
            water.  Most of Autotrol's products are sold to OEM's who
            then utilize them as a component in a water conditioning
            device which is then sold to consumers. 

            LAKEWOOD INSTRUMENTS - In November 1994, the Company
            acquired substantially all of the assets of Lakewood
            Instruments, a Phoenix-based manufacturer of instruments,
            sensors and analyzers used in the measurement of fluid
            characteristics in the chemical water treatment and pure
            water industries.

            WESTERN FILTER COMPANY - In October 1995, the Company
            acquired the assets and operations of Western Filter
            Company, a supplier to the beverage and bottled water
            industry for over 50 years.  Western Filter has extensive
            experience in providing the beverage market with
            conventional water treatment technologies and membrane
            water treatment.

            DESALINATION SYSTEMS - In July 1996, the Company acquired
            Desalination Systems, Inc. ("Desal"), a manufacturer of
            crossflow filtration membrane and membrane elements that
            are marketed worldwide.  Desal, which has facilities in
            Vista, California, has products that extend the range of
            membranes and membrane elements previously offered by the
            Company.  The acquisition extended the Company's
            distribution network for such products.

            AQUAMATIC - In February 1997, the Company acquired
            AquaMatic, Inc., a Rockford, Illinois-based company
            offering a line of specialty valves and controllers for
            the water conditioning market, which are sold through the
            Company's existing distribution channels.

            PURIFICATIONS PRODUCT COMPANY - In December 1997, the
            Company acquired the assets of Purifications Products
            Company ("PPC"), a manufacturer of a line of reverse
            osmosis membrane elements and related products for
            purifying home drinking water and producing high-quality
            water for other applications.  In addition, the PPC
            division offers a line of Silt Density Index instruments
            and a line of UV sterilization products.  These products
            are sold through the Company's existing distribution
            channels.

            MICRON SEPARATIONS, INC. - In February 1998, the Company
            acquired Micron Separations, Inc. ("MSI"), a Westborough,
            Massachusetts-based developer and manufacturer of
            microfilter membrane and membrane products for diagnostic,
            laboratory and industrial use. These products expand the
            Company's range of nylon and cellulosic membrane
            applications.  The products are sold through the Company's
            existing distribution channels.

            MEMBREX CORP. - In April 1998, the Company acquired
            Membrex Corp. of Fairfield, New Jersey.  The acquisition
            gives the Company the most hydrophilic UF membrane in the
            market.  This patented membrane is primarily used to
            separate oil from water and is also used in a variety of
            applications in biotechnology, laboratory and
            petrochemical processes. Membrex also has a patented
            machine using its UF membrane which separates oil from
            aqueous chemical cleaners used in parts cleaning and other
            industrial and commercial applications.  Some Membrex
            products are sold through an exclusive agreement with
            Safety-Kleen Corp. and the remainder through the Company's
            existing distribution channels. 


            PRODUCTS

            The Company's products are divided into two primary
            categories, namely, Consumables and Equipment. 

            CONSUMABLES GROUP:

            The Company's Consumables consist primarily of
            membranes, filter media, membrane elements and filter
            cartridges.  The filtration media and membrane used in the
            Company's Consumables are produced primarily from polymers
            or polymer-based compounds; however, other Consumables
            utilize various inorganic compounds, metals and ceramics.

              MEMBRANES AND ELEMENTS:  Membranes are generally sheets
              of material which, due to their unique characteristics, can
              separate various materials from a fluid.  Membrane elements
              are the combination of membrane, support materials and
              connections which allows the membrane to be broadly
              utilized.

              Membrane elements are typically replaced every 6 to 60
              months, depending upon the severity of the application.  The
              Company manufactures the membrane material and membrane
              elements used in its own systems, and also manufactures
              membrane and membrane elements for other original equipment
              manufacturers (OEM's) who include them as component parts in
              their products.

              The Company's membranes are used in many bioengineering
              processes such as the production of high fructose corn
              sugar, enzyme purification, and purification of
              pharmaceuticals produced by biological processes.  Other
              uses include water purification applications in
              hemodialysis, semiconductor manufacturing, production of
              pure water for beverages, production of ultrapure
              pharmaceutical and boiler feed water, industrial water
              purification and waste removal for pollution control
              compliance.

              In addition, the Company sells its home reverse osmosis
              (HRO) membrane elements to OEM's who package them into
              systems for use in homes, offices and retail vending
              establishments to produce purified drinking water.  The
              Company is registered with the United States Food and Drug
              Administration for the manufacture and sale of certain
              membrane elements used in biological preparations.  The
              Company is also registered with the U.S. FDA for the
              manufacture of Class II medical devices used to purify water
              for hemodialysis. 

              The Company markets its microfiltration normal flow
              membrane for use in a variety of laboratory and medical
              diagnostic applications.  Numerous applications exist for
              the Company's microfilters because of unique features,
              including use in diagnostics, air monitoring and in
              laboratory procedures for cancer and other research.

              FILTER CARTRIDGES:  The Company markets several types
              of replaceable cartridge filters.  Cartridge filters consist
              of the various membranes and filtration media manufactured
              by the Company and third parties together with various end
              caps and other parts that allow them to be used and replaced
              in filtration equipment and systems.  These cartridge
              filters include depth cartridge filters, pleated cartridge
              filters, and rolled cartridge filters. 

              Cartridge filters are manufactured in a range of pore
              sizes and particulate retention ratings.  Cartridge filters
              are designed to retain particles in the filters.  As a
              result, cartridge filters are typically replaced at
              intervals of eight hours to four weeks, depending on the
              particular application.

              The Company's ceramic cartridge filters are marketed
              for use in microfiltration and particulate filtration. 
              Ceramic cartridge filters are used to sterilize
              pharmaceutical solutions and are used in laboratory
              applications, where many analytic and diagnostic procedures
              require purification or sterilization.

              The Company also markets separation elements and
              equipment used in coalescing filtration.  Applications of
              coalescing filtration include removal of contaminants from
              compressed air and gas lines, dewatering of solvents and jet
              fuel, and removal of trace oil from waste water prior to
              disposal.

            EQUIPMENT GROUP:

            The Company manufactures a broad range of equipment
            products ranging from large independent fluid treatment
            systems custom designed for a particular customer and its
            related filtration requirements to instruments used to
            determine the amount of a particular substance in a fluid. 
            The Company's filtration equipment utilizes a wide range of
            filtration techniques including:  crossflow filtration
            (which includes reverse osmosis, nanofiltration,
            ultrafiltration and microfiltration), normal filtration
            (which includes microfiltration and particle filtration),
            coalescing filtration, ion exchange, clarification,
            chromatography, ozonation and distillation.  As a result,
            the Company's Equipment is used in a broad range of
            applications from complete fluid processing systems used in
            beverage production to sensors for detecting the presence of
            various levels of materials.  The Company's Equipment
            products are divided into three categories:  Equipment and
            Pumps, Fluid Controls and Valves, and Systems.  The
            Company's Equipment products are manufactured in multiple
            locations throughout the United States. 

              EQUIPMENT AND PUMPS:

              To provide a complete line of products for the
              production of pure water, the Company manufactures
              distillation equipment, both single-effect and more energy
              efficient multi-effect.  The Company's distillation product
              lines range from laboratory stills to elaborate 5000-gallon-
              per-hour multi-stage purifiers. The Company markets
              distillation and related water purification equipment used
              primarily in the laboratory and pharmaceutical industries.

              The Company markets equipment to generate ozone from
              electricity using corona discharge.  Ozone is becoming
              increasingly important as a bactericide and water purifier
              because it kills bacteria, virus and giardia cysts 10 to
              300 times faster than chlorine.  Ozone is also effective in
              oxidizing trace organic materials in water which are
              precursors of the carcinogenic trihalomethanes.  Ozone can
              also be used to purify solvent-contaminated groundwater and
              is often used to de-color water and wastewater.

              In 1997, the Company announced a partnership with Fuji
              Electric Co., Ltd., Japan and Fuji Electric Corp. of America
              (Fuji) to manufacture high concentration ozone generators
              using proprietary Fuji technology and components.  This
              partnership will provide the Company a strong entry into the
              municipal water treatment market, as well as pulp and paper
              and other large-scale oxidation applications.  As part of
              the agreement, the Company has the rights to manufacture and
              sell such equipment world-wide except for Japan and Korea.

              Other types of equipment manufactured by the Company
              include centrifugal, diaphragm, and bellows pumps;
              electronic controllers to operate precision valves for water
              conditioning; flow control and measuring devices and
              instrumentation; and housings and specialty holders and
              devices for containing and retaining various membranes and
              filters.

              The Company markets a line of multi-stage centrifugal
              pumps.  These pumps were developed by the Company to meet
              the need for dependable high pressure pumps and are
              available in 60 standard sizes with flows ranging from 3
              gallons per minute to 500 gallons per minute and pressure
              capabilities from 25 pounds per square inch (psi) to
              500 psi.  The pumps are capable of operating in series to
              obtain 1000 psi for seawater desalting and other high
              pressure applications.

                CONTROLS AND VALVES:

                The Company is a leader in the manufacture of the
                controllers and valves used to effect ion exchange
                technology.  The most used ion exchange process is for water
                softening where the ions of calcium and magnesium are
                replaced with sodium to reduce soap usage, improve boiler
                operation and improve cleaning.  Another ion exchange
                application is to polish ultrapure water for electronics
                manufacture and high-pressure boiler feed. 

                The Company markets totalizing flow meters and
                electronic controllers made of corrosion resistant Noryl
                plastic, as well as a line of Teflon PTFE fluid control
                products including valves, fittings and flow meters used in
                the electronics, pharmaceutical and chemical industries.

                The Company markets both analog and digital products
                for chemical water treatment and monitoring.  The
                instruments are used to measure and control conductivity,
                pH, ORP, chlorine, specific ions, trihalomethanes (THM's)
                and solvents in water, such as trichloroethylene.  The
                instruments are capable of being used in local operating
                network (LON) communications and data acquisition.

                CUSTOM EQUIPMENT AND SYSTEMS:

                The Company also manufacturers crossflow and normal
                filtration machines.  Such machines are comprised of one or
                more membrane elements, cartridge filters, pumps, valves,
                controls, transformers, heat exchangers, pipes and a steel
                frame on which the components are mounted.  The size and
                number of membrane elements and filters can vary greatly. 
                Pumps, pipes and frames of various sizes can be combined and
                configured to accommodate the membrane elements or filters
                required for various fluid handling or separation tasks.

                The systems sold by the Company are comprised of one or
                more machines or pieces of equipment designed and
                manufactured by the Company as well as ancillary equipment,
                such as additional pumps, heat exchangers and holding tanks.
                The type, size and number of machines and the ancillary
                equipment included in a system will vary with the nature and
                size of the fluid separation task. 


            REPLACEABLE AND EQUIPMENT SALES

            The following table shows the percentage of net sales
            during the past five years attributable to the Company's
            fluid processing and handling equipment compared to its
            replaceable components:

                      Year Ended                   Replaceable
                      December 31    Equipment     Components
                      -----------    ---------     -----------
                         1998           48%            52%
                         1997           46%            54%
                         1996           49%            51%
                         1995           48%            52%
                         1994           51%            49%
                         1993           49%            51%

            As a result of a Company-wide reorganization on July 1, 1998
            and to meet new SEC reporting requirements, the above sales
            comparison will no longer be reported.  Instead, business
            results will be reported based on the two segments previously
            discussed (Consumables and Equipment).

            For the last six months of 1998, the Consumables Group
            was 41% of total sales and the Equipment Group made up 59%
            of sales.  Although we will discontinue our previous method
            of reporting, it is still our goal to have an equal balance
            of replaceable sales to equipment sales.


            SALES AND MARKETING

            As a result of our broad range of Equipment and
            Consumables, the Company's Equipment and Consumables are
            used in the purification of water and industrial solutions,
            dewatering and recycling of commercial and industrial
            fluids, pollution control and seawater desalting.  The
            Company's principal domestic and international markets, from
            which it derives more than 50% of its sales, include the
            potable water, health care, biotechnology, food and
            beverage, electronics, chemical processing and power
            generation industries.   

            The Company focuses the marketing of its products through
            four selling groups:

               1.  Custom equipment and systems.

               2.  Components and product sales.

               3.  Catalog and telephone sales.

               4.  International

            These sales groups are supported by application engineers
            and market support personnel. 

            The Company markets its custom machines and systems
            through its direct sales force.  The Company's standard
            products are marketed to a network of independent
            distributors with the help of Company district managers. 
            These distributors provide world-wide installation service
            and stocking of a wide range of the Company's standard
            products.  Some sales are made directly to certain of the
            Company's largest customers and to other manufacturers of
            filtration equipment and systems.

            The Company's marketing activities include appearances
            at trade shows, direct mail campaigns, advertisements in
            professional and trade journals and appearances before
            professional organizations.  The Company participates with
            its customers in planning the systems in which its products
            are to be used, particularly if new applications are
            involved.  In some cases, the sale of a system designed for
            a particular customer may result from an engineering and
            service relationship which has extended over several years.


            RESEARCH AND DEVELOPMENT

            Research and development activities emphasize product
            development and applied research, with the goal of
            developing proprietary products.  Such expenditures totaled
            $9,913,000 in 1998, $10,635,000 in 1997, and $10,937,000 in
            1996.


            PATENTS AND TRADEMARKS

            The Company has been granted domestic and certain
            foreign trademarks on numerous product names, and on its
            logo-types.  The Company holds domestic and foreign patents
            on certain of its filter media, filters, controlling valves,
            machine designs and other products.  Although the Company
            believes that its patents have value, the Company's business
            is not dependent on any patent or group of related patents.
            The Company considers its technological position to be
            based primarily on its proprietary manufacturing methods,
            innovative engineering and marketing expertise.


            EMPLOYEES

            As of December 31, 1998, the Company employed 1,360 persons
            including 213 holding engineering or technical degrees.


            COMPETITION

            The Company experiences competition from a variety of
            sources with respect to virtually all of its products,
            although the Company knows of no single entity that competes
            with it across the full range of its products and systems. 
            Competition in the markets served by the Company is based on
            a number of factors, which may include price, technology,
            applications experience, know-how, availability of
            financing, reputation, product warranties, reliability,
            service and distribution.

            With respect to the Company's membrane and related
            water treatment equipment business activity, there are a
            number of companies, including several sizable chemical
            companies, that manufacture membranes, but not equipment. 
            There are numerous smaller companies, primarily fabricators,
            that build water treatment and desalination equipment, but
            which generally do not have their own proprietary membrane
            technology.  A limited number of companies manufacture both
            membranes and equipment.  In ozone and distillation
            equipment, there are both large and small competitors with
            no single dominant competitor.  In water softener controls
            and valves, the Company has three primary and numerous
            secondary competitors.  Some competitors sell only
            controller valves and some sell complete softeners.  The
            Company has numerous competitors in its conventional water
            treatment and filtration products business activities. 

            With respect to the Company's disposable filter and lab
            products, two companies, Pall and Millipore, dominate the
            industry with several smaller companies competing in
            selected product lines. 

            With respect to the Company's pump and fluid handling
            products, there are numerous competitors of larger size and
            with greater resources than the Company.  Some competitors
            have significantly broader product lines than the Company. 

            The Company is unable to state with certainty its
            relative market position in all aspects of its business.
            Many of its competitors have financial and other resources
            greater than those of the Company.


            RAW MATERIALS

            The principal raw materials used by the Company are
            various plastic materials including polyvinyl chloride,
            polypropylene, Noryl PPO, Nylon cellulose acetate,
            polycarbonate, polyester, polysulfone, and PTFE; ceramic and
            glass materials, stainless steel, steel, brass, copper,
            titanium, silver and various other synthetic materials, all
            of which are normally available from sources within the
            continental United States.  Most raw materials used by the
            Company are available from multiple sources of supply.  A
            limited number of materials are proprietary products of
            major chemical companies which, if not available, would have
            a material effect on the Company's sales and profits.  The
            Company believes it could find substitutes for these
            materials if they should become unavailable, but has no
            assurance that the substitute would perform as well or be
            priced as favorably.

            To date, the Company has experienced no difficulty in
            securing any of its needed raw materials and components.


            CUSTOMERS

            No one customer accounted for 10 percent or more of the
            Company's consolidated revenue in 1998, 1997, or 1996.


            BACKLOG

            The dollar amount of the Company's backlog of orders
            considered to be firm at December 31, 1998, was $21.6
            million.  The comparable backlog at December 31, 1997, was
            $28.2 million.  The Company expects that nearly all orders
            included in the backlog at December 31, 1998, will be filled
            during the 1999 fiscal year.  The Company does not believe
            that its backlog at any time is necessarily indicative of
            annual sales.  The business of the Company is not subject to
            significant seasonal variations. 


            GOVERNMENTAL REGULATION

            Certain applications of the Company's reverse osmosis
            and ultrafiltration products and distillation equipment are
            subject to governmental regulation.  Products used for
            fractionation of cheese whey for human consumption are
            subject to regulation by the United States Department of
            Agriculture.  Reverse osmosis, ultrafiltration and
            distillation systems used in medical applications,
            particularly the systems used in artificial kidney dialysis
            equipment and pharmaceutical water for injection, are
            subject to regulation by the United States Food and Drug
            Administration.  Ultrafiltration and microfiltration
            products used for biological separations are subject to
            regulation by the United States Food and Drug
            Administration.

            To date, compliance with federal, state and local
            provisions relating to the protection of the environment has
            had no material effect upon the capital expenditures,
            earnings or competitive position of the Company.


            FOREIGN OPERATIONS

            Substantially all of the Company's operations and
            assets are located in the United States.  The Company has
            sales offices and distribution facilities in France,
            Thailand, Switzerland, Germany, Hong Kong, Japan, Singapore
            and China.  Limited assembly is conducted in Europe and
            Asia.  The profitability of domestic and foreign sales is
            substantially equal.  Sales to Canada are made on the same
            trade terms as are available to U.S. customers.

            Large export sales are primarily made on the basis of
            confirmed irrevocable letters of credit or time drafts to
            selected customers in U.S. dollars.  Therefore, the Company
            believes that currency fluctuation or political and economic
            instability do not constitute substantial risks.  See Note
            13 of Notes to Consolidated Financial Statements for a
            breakdown of the Company's foreign operations and export
            sales by geographic area.


            CERTAIN FACTORS

            In addition to the factors discussed elsewhere in the
            Company's Annual Report to Shareholders or this Form 10-K,
            such as intellectual property and other technological risks,
            regulatory risks, environmental risks and Year 2000 risks,
            the following are some important factors that could cause
            actual results or events to differ materially from those
            contained in any forward-looking statements made by or on
            behalf of the Company. 

              EARNINGS VARIATIONS:

              The sale of capital equipment within the water
              purification and fluid filtration industry is cyclical and
              influenced by various economic factors including interest
              rates and general fluctuations of the business cycle.  A
              significant portion of the Company's revenues are derived
              from capital equipment sales.  While the Company sells
              capital equipment to customers in diverse industries and in
              global markets, cyclicality of capital equipment sales and
              instability of general economic conditions, including those
              in Asia and Latin America and certain other markets, could
              have a material adverse effect on the Company's revenues and
              profitability. 

              Operating results from the sale of water purification
              and fluid filtration industry also can be expected to
              fluctuate significantly as a result of the limited pool of
              existing and potential customers for these systems, the
              timing of new contracts, possible deferrals or cancellations
              of existing contracts and the evolving and unpredictable
              nature of the markets for water purification systems.  As a
              result of these and other factors, the Company's operating
              results may be subject to quarterly or annual fluctuations.
              There can be no assurance that at any given time the
              Company's operating results will meet or exceed stock market
              analysts' expectations.

              COMPETITION:

              All of the markets in which the Company competes are
              highly competitive, and most are fragmented, with numerous
              regional and local participants.  There are competitors of
              the Company in certain markets that are divisions or
              subsidiaries of companies that have significantly greater
              resources than the Company.  Competitive factors include
              price, technical expertise, product quality and
              responsiveness to customer needs, including service and
              technical support.  The Company competes not only with a
              large number of independent wholesalers and with other
              distribution chains similar to the Company, but also with
              manufacturers who sell directly to customers.  The Company's
              HRO business also competes with companies with national
              distribution networks, businesses with regional scope, and
              local product assemblers or service companies, as well as
              retail outlets.  The Company believes that there are
              thousands of participants in the residential water business.
              The HRO business competes principally on the basis of
              price, product quality and "taste," service, distribution
              capabilities, geographic presence and reputation. 
              Competitive pressures, including those described above, and
              other factors could cause the Company to lose market share
              or could result in significant price erosion, either of
              which could have a material adverse effect upon the
              Company's financial position, results of operations and cash
              flows.

              RISKS RELATED TO ACQUISITIONS:

              The Company has, since 1987, acquired a number of
              United States-based companies and product lines.  The
              Company plans to continue to consider and potentially pursue
              acquisitions that expand the segments of the water and
              wastewater treatment and water-related industries in which
              it participates, complement its technologies, products or
              services, broaden its customer base and geographic areas
              served and/or expand its global distribution network, as
              well as acquisitions which provide opportunities.  The
              Company's acquisition strategy entails the potential risks
              inherent in assessing the value, strengths, weaknesses,
              contingent or other liabilities and potential profitability
              of acquisition candidates and in integrating the operations
              of acquired companies.  Although the Company believes that
              it has generally been successful in pursuing acquisitions,
              there can be no assurance that acquisition opportunities
              will continue to be available, that the Company will have
              access to the capital required to finance potential
              acquisitions, that the Company will continue to acquire
              businesses or that any business acquired will be integrated
              successfully or prove profitable.

              PROFIT UNCERTAINTY IN FIXED-PRICE CONTRACTS:

              A significant portion of the Company's revenues are
              generated under fixed price contracts.  To the extent that
              original cost estimates are inaccurate, scheduled deliveries
              are delayed or progress under a contract is otherwise
              impeded, revenue recognition and profitability from a
              particular contract may be adversely affected.

              RISKS OF DOING BUSINESS IN OTHER COUNTRIES:

              The Company sells a significant amount of its product
              in markets outside the United States.  While these
              activities may provide important opportunities for the
              Company to offer its products and services internationally,
              they also entail the risks associated with conducting
              business internationally, including the risk of currency
              fluctuations, slower payment of invoices, the lack in some
              jurisdictions of well-developed legal systems,
              nationalization and possible social, political and economic
              instability.


            ITEM 2.  PROPERTIES

            The executive offices and principal manufacturing facilities
            of the Company are located in Minnetonka, Minnesota, a
            suburb of Minneapolis.

            A summary of the Company's main operating facilities is
            as follows:


            LOCATION         STATUS       SIZE       FUNCTION
            --------         ------       ----       --------   
            Minnetonka, MN   Owned    309,600 sq ft  Sales, Manufacturing,
                                                     Warehouse

            Vista, CA        Owned    110,000 sq ft  Sales, Manufacturing,
                                                     Warehouse

            Milwaukee, WI    Owned    103,700 sq ft  Sales, Manufacturing,
                                                     Warehouse

            Rockford, IL     Owned     58,400 sq ft  Sales, Manufacturing,
                                                     Warehouse

            Phoenix, AZ      Owned     57,600 sq ft  Sales, Manufacturing,
                                                     Warehouse

            Syracuse, NY     Owned     48,500 sq ft  Sales, Manufacturing,
                                                     Warehouse

            Westborough, MA  Leased    46,800 sq ft  Sales, Manufacturing,
                                                     Warehouse

            Rockland, MA     Leased    38,200 sq ft  Sales, Manufacturing,
                                                     Warehouse

            Fairfield, NJ    Leased    23,800 sq ft  Research & Development

            Upland, CA       Leased    22,000 sq ft  Sales, Manufacturing,
                                                     Warehouse

            Denver, CO       Owned     20,700 sq ft  Warehouse

            Escondido, CA    Leased    20,000 sq ft  Manufacturing

            Ft. Lauderdale,  Leased    20,000 sq ft  Sales, Warehouse

            Le Mee, France   Owned     18,300 sq ft  Sales, Manufacturing,
                                                     Warehouse

            Emmetsburg, IA   Leased     8,800 sq ft  Manufacturing, Warehouse

            Bryan, TX        Owned      2,500 sq ft  Manufacturing, Warehouse

            Total Owned               729,300 sq ft

            Total Leased              179,600 sq ft

            Total Owned and Leased    908,900 sq ft

            Certain borrowings of the Company are collateralized by
            real property of the Company.

            The current manufacturing facilities are adequate for
            intermediate-term operations.  In addition, the Company
            leases space in Thailand, China, Germany, Japan, Hong Kong,
            Switzerland and Singapore that is used primarily for sales
            activities. 


            ITEM 3.  LEGAL PROCEEDINGS

            The Company is currently involved in several lawsuits
            incidental to its business. Management does not believe that
            any of the lawsuits will have a material adverse effect on
            the Company's financial position or results of operations.


            ITEM 4.  SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

            No matter was submitted to a vote of the Company's
            security holders during the fourth quarter of the fiscal
            year that ended December 31, 1998. 

                         EXECUTIVE OFFICERS OF THE REGISTRANT

                                                                      OFFICER
               NAME AND AGE             POSITION WITH COMPANY          SINCE
            --------------------       -----------------------        -------
            D. Dean Spatz (54)         Chief Executive Officer         1969
                                       and Chairman of the Board

            Ruth Carol Spatz (54)      Secretary                       1969

            Howard W. Dicke (61)       Vice President Human Resource   1978
                                       and Corporate Development,
                                       and Treasurer

            L. Lee Runzheimer (56)     Chief Financial Officer         1988

            Roger S. Miller (40)       Sr. Vice President Corporate    1998
                                       Sales & Marketing

            Kenneth E. Jondahl (42)    Vice President Commercial       1991
                                       Development

            Andrew T. Rensink (42)     Vice President Quality and
                                       Regulatory Affairs              1991

            Phillip M. Rolchigo (37)   Vice President Research &       1998
                                       Development

            Kenton C. Toomey (51)      Executive Vice President        1997
                                       Operations

            Bjarne N. Nicolaisen (55)  Vice President International    1998
            

            All of the executive officers have been officers of the
            Company for more than five years except the following: 

            Mr. Miller joined Osmonics in 1993 as a product manager
            for pumps.  Previously, Mr. Miller managed sales and
            marketing for a machine tool manufacturer and for a capital
            equipment manufacturer in the water treatment industry. 

            Mr. Nicolaisen came to Osmonics with the merger with
            Desalination Systems, Inc. in 1996.  Mr. Nicolaisen began
            his career as a chemical engineer and regional sales manager
            for Radiometer A/S in Denmark.  He then joined DDS Group as
            a sales manager in the reverse osmosis division, eventually
            moving to the U.S. as sales director for dairy equipment in
            1980. Mr. Nicolaisen became vice president of sales and
            marketing for Desalination Systems in 1987. 

            Dr. Rolchigo came to Osmonics from Membrex Corp., which
            Osmonics acquired in 1998.  Dr. Rolchigo is the principal
            inventor of advanced vortex flow filtration technology.  His
            technical expertise spans diverse industries from
            environmental waste to pharmaceutical processing.  He has
            served as a research affiliate in chemical engineering for
            MIT, and belongs to numerous industry organizations.  

            Mr. Toomey joined Osmonics in April of 1997 as Vice
            President Operations.  Prior to that he had been the Vice
            President of Operations for DeZurik, a unit of General
            Signal.  Previously, throughout his 26 years with 3M
            Company, Mr. Toomey held numerous director and management
            positions in several 3M business units including plant
            manager of the Dental Products Division. 

            All executive officers are elected annually by, and
            serve at the direction of, the Board of Directors.  D. Dean
            Spatz and Ruth Carol Spatz are husband and wife.


                                     PART II

            ITEM 5.  MARKET FOR THE REGISTRANT'S COMMON EQUITY AND
                     RELATED SHAREHOLDER MATTERS

            "Common Stock Data," and "Notes to Consolidated
            Financial Statements," pages 16-21 of the Annual Report to
            Shareholders, are incorporated herein by reference.  As of
            March 17, 1999 there were 2,313 shareholders of record.

            The Company has not paid cash dividends on its common
            shares.  The Board of Directors currently intends to retain
            its earnings for the expansion of the Company's business.
            The Company has issued promissory notes which contain a
            covenant limiting the payment of dividends to shareholders.
            At December 31, 1998, approximately $5,000,000 of retained
            earnings was restricted under this covenant. 


            ITEM 6.  SELECTED FINANCIAL DATA

            "Selected Financial Data," page 29 of the Annual Report
            to Shareholders, is incorporated herein by reference.


            ITEM 7.  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
                     CONDITION AND RESULTS OF OPERATIONS

            "Management's Discussion and Analysis of Financial
            Condition and Results of Operations," pages 22-25 of the
            Annual Report to Shareholders, is incorporated herein by
            reference. 


            ITEM 8.  FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

            The following consolidated financial information of the
            Registrant and its subsidiaries, included in the Annual
            Report to Shareholders, is incorporated herein by reference:

                                                                Page(s)
                                                                -------
                Consolidated Statements of Income . . . . . . . .  12

                Consolidated Balance Sheets  . . . . . . . . . . . 13

                Consolidated Statements of Cash Flows  . . . . . . 14

                Consolidated Statements of Changes in
                      Shareholders' Equity  . . . . . . . . . . .  15

                Notes to Consolidated Financial Statements . .  16-21

                Independent Auditors' Report   . . . . . . . . . . 25

                Quarterly Income Data  . . . . . . . . . . . . . . 26


                                     PART III

            ITEM 10.  DIRECTORS

            The information required by this item is incorporated
            herein by reference to the definitive Proxy Statement to be
            filed with the Securities and Exchange Commission within 120
            days after the close of the Company's fiscal year ended
            December 31, 1998 and forwarded to stockholders prior to the
            Company's 1999 Annual Meeting of Stockholder (the "1999
            Proxy Statement").


            ITEM 11.  EXECUTIVE COMPENSATION

            The information required by this Item is incorporated
            herein by reference to the 1999 Proxy Statement.


            ITEM 12.  SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS
                      AND MANAGEMENT

            The information required by this Item is incorporated
            herein by reference to the 1999 Proxy Statement.


            ITEM 13.  CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

            The information required by this Item is incorporated
            herein by reference to the 1999 Proxy Statement. 


                                     PART IV

            ITEM 14.  EXHIBITS, FINANCIAL STATEMENT SCHEDULE, AND
                      REPORTS ON FORM 8-K

                   (a) (1)  Financial Statements

                            The consolidated financial statements of the
                            Registrant and its subsidiaries, included in
                            the Annual Report to Shareholders, are
                            incorporated by reference in Item 8, and are
                            also incorporated herein by reference.

                   (a) (2)  Financial Statement Schedule

                            Reports of Independent Public Accountants on
                            Supplemental Schedule to the Consolidated
                            Financial Statements.

                            Valuation and qualifying accounts.

                            Schedules not listed above have been omitted
                            because they are either not applicable, not
                            material or the required information has
                            been given in the financial statements or in
                            the notes to the financial statements.

                       (2)  Agreement and Plan of Merger among
                            Desalination Systems, Inc., Osmonics, Inc.
                            and DSI Acquisition Corp. dated
                            May 17, 1996.  (Incorporated herein by
                            reference to Exhibit 2 to Registration
                            Statement on Form S-3, File No. 33-05029.)

                           (3)A. Certificate of Incorporation of the
                                 Registrant, as amended.  (Incorporated
                                 herein by reference to Exhibit 3.1 to
                                 Registration Statement on Form S-2,
                                 File No. 33-336.)  Certificate of
                                 Amendment.  (Incorporated herein by
                                 reference to Exhibit (3)A on Form 10-K
                                 for fiscal year ended December 31, 1987,
                                 File No. 0-8282.)

                              B. By-Laws of the Registrant. 
                                 (Incorporated herein by reference to
                                 Exhibit 3.2 to Registration Statement
                                 on Form S-2, File No. 33-336.)

                           (4)A. Note Purchase Agreement dated July 12,
                                 1991. (Incorporated herein by
                                 reference to Annual Report on Form 10-K
                                 for fiscal year ended December 31, 1991.)

                          (10)A.* 1993 Stock Option Plan and related
                                  form of stock option agreement. 
                                  (Incorporated herein by reference to
                                  Annex C of the Registrant's Joint
                                  Proxy Statement/Prospectus dated
                                  September 10, 1993.)

                              B.  Stock Option Agreement with Michael L.
                                  Snow, Director.  (Incorporated herein
                                  by reference to Annual Report on Form
                                  10-K for fiscal year ended
                                  December 31, 1993.)

                              D.  1995 Employee Stock Purchase Plan. 
                                  (Incorporated herein by reference to
                                  the Registrant's Proxy Statement dated
                                  March 27, 1995.)

                              E.* 1995 Director Stock Option Plan. 
                                  (Incorporated herein by reference to
                                  the Registrant's Proxy Statement dated
                                  March 27, 1995.)

                                  * Denotes Executive Compensation Plan.

                            (13)  1998 Annual Report to Shareholders. 
                                  (Only those portions incorporated
                                  herein by reference shall be deemed
                                  filed with the Commission.)

                            (21)  Subsidiaries of the Registrant.

                            (23)  Consent of Deloitte & Touche LLP.

                       (b)  Reports on Form 8-K

                            No reports on Form 8-K were filed during the
                            quarter ended December 31, 1998.


                                     SIGNATURES

            Pursuant to the requirements of Section 13 or 15(d) of
            the Securities Exchange Act of 1934, the registrant has duly
            caused this report to be signed on its behalf by the
            undersigned, thereunto duly authorized.

                                                OSMONICS, INC.

                                                By  /s/ D. Dean Spatz  
                                                ------------------------
                                                D. Dean Spatz, President

            Dated:  March 30, 1999


            Pursuant to the requirements of the Securities Exchange
            Act of 1934, this report has been signed below by the
            following persons on behalf of the registrant and in the
            capacities and on the dates indicated:

                 Signatures                 Title                 Date
            --------------------   ----------------------    --------------

            /s/L. Lee Runzheimer   Chief Financial           March 30, 1999
               L. Lee Runzheimer   Officer
                                   (Principal Finance and
                                   Accounting Officer)

            /s/Howard W. Dicke     Vice President Human      March 30, 1999
               Howard W. Dicke     Resources and
                                   Corporate Development,
                                   and Treasurer

            /s/Ruth Carol Spatz    Director                  March 30, 1999
               Ruth Carol Spatz

            /s/Michael L. Snow     Director                  March 30, 1999
               Michael L. Snow

            /s/Ralph E. Crump      Director                  March 30, 1999
               Ralph E. Crump

            /s/Verity C. Smith     Director                  March 30, 1999
               Verity C. Smith

            /s/Charles W. Palmer   Director                  March 30, 1999
               Charles W. Palmer

            /s/William Eykamp      Director                  March 30, 1999
               William Eykamp

            /s/D. Dean Spatz       President, Chairman of    March 30, 1999
               D. Dean Spatz       the Board and Director
                                   (Principal Executive
                                   Officer)