UNITED STATES

               SECURITIES AND EXCHANGE COMMISSION

                      Washington, DC 20549

                            FORM 10-K

[ X ]  ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
       SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 1997

                               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 Number          1-7211

                     Ionics, Incorporated
     (Exact name of registrant as specified in its charter)

            Massachusetts                    04-2068530
   State or other jurisdiction of      (I.R.S. Employer
   incorporation or organization        Identification Number)

 65 Grove Street, Watertown, Massachusetts         02172
(Address of principal executive offices)        (Zip Code)

Registrant's telephone number, including area code: 617-926-2500

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

   Title of each class         Name of each exchange on which registered

Common Stock, $1 par value              New York Stock Exchange

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

                                  None
                            (Title of Class)

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 any amendment to this
Form 10-K.      [X]
/1




State the aggregate market value of the voting and non-voting
common equity held by non-affiliates of the registrant.  The
aggregate market value shall be computed by reference to the price
at which the common equity was sold, or the average bid and asked
prices of such common equity, as of a specified date within 60
days prior to the date of filing.  The aggregate market value of
the Common Stock of the registrant held by non-affiliates as of
March 20, 1998 was $684,868,264 (15,698,986 shares at $43 5/8 per
share) (includes shares owned by a trust for the indirect benefit
of a non-employee director, and by a trust for the indirect
benefit of a spouse of a non-employee director).


           (APPLICABLE ONLY TO CORPORATE REGISTRANTS)

     Indicate the number of shares outstanding of each of the
registrant's classes of common stock, as of the latest practicable
date.  As of March 20, 1998, 16,053,335 shares of Common Stock, $1
par value, were issued and outstanding.

               DOCUMENTS INCORPORATED BY REFERENCE

Portions of the 1997 Annual Report to Stockholders. Parts I, II
                                                    (for Item 201
                                                    information)
                                                    and IV

Portions of the Definitive Proxy Statement for
the Annual Meeting of Stockholders to be held
on May 7, 1998.                                     Part III



























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                             PART I

Item 1.  BUSINESS

     Ionics, Incorporated ("Ionics," the "Company," or the
"Registrant") is a leading water purification company engaged
worldwide in the supply of water and of water treatment equipment
through the use of proprietary separations technologies and
systems.  Ionics' products and services are used by the Company or
its customers to desalt brackish water and seawater, to purify and
supply bottled water, to treat water in the home, to manufacture
and supply water treatment chemicals and ultrapure water, to
process food products, recycle and reclaim process water and
wastewater, and to measure levels of water-borne contaminants and
pollutants.  The Company's customers include industrial companies,
consumers, municipalities and utilities.

     The Company's business activities are divided into three
segments:  Membranes and Related Equipment; Water, Food and
Chemical Supply; and Consumer Products, which in 1997 accounted
for approximately 47%, 32% and 21% of revenues, respectively.
Approximately 41% of the Company's 1997 revenues were derived from
foreign sales or operations.  The Company has been pursuing a
strategy of expanding beyond its traditional focus of selling
desalination plants and equipment by also owning and operating its
own equipment to produce and sell water, food and chemicals.  In
1997, the Water, Food and Chemical Supply and Consumer Products
business segments accounted for 58% of the Company's earnings
before interest, taxes and minority interest.

     Currently, the Company's three business segments encompass
ten business areas or applications described by the Company as its
"Ten-Cylinder EngineSM" strategy.  The following description of
the Company's business segments is further divided into a
description of these business areas.

     Nearly fifty years ago, the Company pioneered the development
of the ion-exchange membrane and the electrodialysis process.
Since that time, the Company has expanded its separations
technology base to include a number of membrane and non-membrane-
based separations processes which the Company refers to as "The
Ionics ToolboxSM."  These separations processes include
electrodialysis reversal (EDR), reverse osmosis (RO),
ultrafiltration (UF), microfiltration (MF), electrodeionization
(EDI), electrolysis, ion exchange, carbon adsorption, and thermal
processes such as evaporation and crystallization, as well as
solvent extraction and recovery processes.  The Company believes
that it is the world's leading manufacturer of ion-exchange
membranes and of membrane-based systems for the desalination of
water.

     The Company was incorporated in Massachusetts in 1948.  The
Company's principal executive offices are located at 65 Grove
Street, Watertown, Massachusetts 02172.



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                               I-1




Financial Information About Business Segments

     The information contained in Note 15 of Notes to Consolidated
Financial Statements contained in the Company's Annual Report to
Stockholders for the year ended December 31, 1997 is incorporated
herein by reference.

Membranes and Related Equipment

     The Company's Membranes and Related Equipment business
segment, which accounted for approximately 47% of revenues in
1997, is composed primarily of membrane-based and other advanced
technology systems for the municipal and industrial markets, and
is divided into four market areas:  desalination and related water
treatment equipment; wastewater treatment equipment; instruments;
and ultrapure water equipment.  The Company also fabricates
specially designed products ranging from intricate small parts to
very large multi-ton assemblies for various industrial and
defense-related applications.

     1.    Desalination and Related Water Treatment Equipment

     Opportunities for the sale of desalination and related
water treatment equipment arise from changes in the needs of
people and municipalities, from industrial shifts and growth,
and from environmental concerns.  With less than 1% of the
total water on the planet fresh and usable, desalination has
played an important role in creating new water sources.

     The Company sells a wide spectrum of products and systems to
serve this market which utilize technologies including
electrodialysis reversal(EDR), ion exchange, electrodeionization,
reverse osmosis, ultrafiltration, ozonation and carbon
adsorption.  Depending on the customers' needs, the Company
provides standardized versions of systems utilizing one or more
of the technologies mentioned, or can supply complete turnkey
plants that may include standardized models as well as peripheral
water treatment equipment, complete engineering services, process
and equipment design, project engineering, commissioning,
operator training and field service.

     In 1997, the Company introduced the new Ionics 2020TM EDR
system, a third-generation brackish water desalination system
incorporating several new, patented improvements at reduced cost.

     2.    Wastewater Treatment Equipment

     The market for wastewater treatment, recycle and reuse has
shown significant growth as world demand for water of specified
quality continues to increase and as regulations limiting waste
discharges to the environment continue to mount.  The wastewater





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                               I-2



market is increasingly driven by the concept of total water
management, which involves the recognition that the water streams
which enter, leave or become part of a process can be managed to
achieve overall economic efficiencies.  Ionics services the
wastewater market with brine concentrators and crystallizers,
traditional wastewater treatment equipment, and special
electrodialysis reversal membrane-based concentrators for recycle
and reuse.

     The Company designs, engineers and constructs brine
concentrators, evaporators and crystallizers which are used to
clean, recover and recycle wastewater, particularly in zero
liquid discharge industrial uses.  Such systems may also
incorporate electrodialysis reversal membrane systems as
preconcentrators.  Ionics also holds a license for a patented
solvent extraction technology which separates contaminated
sludges, sediments and soils into oil, water and solids.  This
technology has potential use for cleanup of toxic organic
materials at contaminated sites.

     Ionics also designs, engineers and constructs customized
systems for industrial wastewater customers which may include
conventional treatment systems as well as advanced separation
technologies such as electrodialysis reversal, reverse osmosis,
electrolysis and microfiltration.  Typical industrial customers
are power stations, chemical and petrochemical plants,
metal-working and automobile factories, textile manufacturers and
a variety of other industrial applications.  The Company also
provides custom and packaged sewage treatment systems for
municipalities.

     3.    Instruments

     The Company sells instruments to measure water quality for
industrial and government customers.  In 1996, the Company
acquired Sievers Instruments, Inc. (Sievers), located in Boulder,
CO.  Sievers manufactures, among other instruments, total organic
carbon (TOC) monitors which are sensitive to the parts per
trillion range and are used primarily in ultrapure water
applications in the semiconductor and pharmaceutical industries.
Sievers TOC monitors complement the Company's TOC monitor line
for process water and wastewater applications.  The Company's
instrument products, which are used both in the laboratory and
on-line, measure and detect, among other things, total carbon,
TOC, sulfur, nitric oxide, chemical oxygen demand and total
oxygen demand.  The Company also sells instruments for the
measurement of dissolved metals and specific chemical analyzers
for ammonia, phosphates, nitrates and chlorine.








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                               I-3



     4(a). Ultrapure Water Equipment

     Ultrapure water, which has been purified by a series of
processes to the degree that remaining impurities are measured in
parts per billion or trillion, is required for specialized
industrial uses.  The demand for technologically advanced
ultrapure water equipment and systems has increased as the
industries which use ultrapure water have become more
knowledgeable about their quality requirements.  Ultrapure water
needs are particularly important in the semiconductor,
pharmaceutical, petroleum and power generation industries.  The
semiconductor industry in particular has increasingly demanded
higher purity water as the circuits on silicon wafers have become
more densely packed.

     The Company supplies sophisticated ultrapure water systems
to the semiconductor, electronics and power industries which
utilize a combination of electrodialysis reversal, ion- exchange,
electrodeionization, reverse osmosis and
ultrafiltration technologies.  These systems are either trailer-
mounted or land-based and vary from standardized modules to large
multimillion dollar systems, depending on the customer's
requirements.

Water, Food and Chemical Supply

     The Water, Food and Chemical Supply business segment
accounted in 1997 for approximately 32% of the Company's
revenues.  The Company's strategy is to sell, where appropriate,
water, food products and chemicals produced by its membrane-based
equipment, rather than selling the equipment itself.  The Water,
Food and Chemical Supply business segment can be divided into
four market areas:  ultrapure water supply; drinking water
supply; chemical supply; and food processing.

     4(b).  Ultrapure Water Supply

     In industries such as power generation, semiconductors,
pharmaceuticals and biotechnology, ultrapure water is critical to
product quality and yield.  Depending on the composition and
quantity of the impurities to be removed or treated, any one of
several membrane separations methods can be utilized to provide
ultrapure water to the customer.  Ionics has pioneered in the
application of three membrane technologies (EDR, RO and UF)
combined together in a mobile system called the "triple membrane"
trailer for use in the commercial processing of ultrapure water.
Ionics provides ultrapure water services and the production and
sale of ultrapure water from trailer-mounted units at customer
sites.








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                               I-4



     Ionics has also commercially implemented its new
electrodeionization (EDI) technology in the production of
ultrapure water.  EDI is a continuous, electrically driven,
membrane-based water purification process which produces
ultrapure water without the use of strong chemical regenerants,
such as sulfuric acid and caustic soda, which are commonly
required.  The Company's TMT-II trailers utilize a combination of
EDI, RO and UF technologies and represent what the Company
believes to be the most advanced technology used in the
commercial processing of ultrapure water.

     At the end of 1997, Company-owned equipment for the
production of ultrapure water under contract with companies in
various industries had a total capacity of approximately 15,000
gallons per minute.

     In January 1996, the Company acquired Apollo Ultrapure Water
Systems, Inc., based near Los Angeles, enabling the Company to
provide additional resources to service the growing Southern
California ultrapure water market.

     One of the Company's important ultrapure water service
activities is ion-exchange regeneration services, which are
provided at four U.S. locations.  The Company also provides
system sanitization and high-flow deionization services at
customer sites.

     5.    Drinking Water Supply

     Ionics' position as a seller of purified or treated water
has evolved from its traditional role as a supplier of water
treatment equipment.  In certain situations, opportunities are
available for the Company to provide a complete service package
involving financing, construction, operation and maintenance of
water treatment facilities.

     Ionics, through its wholly owned subsidiary, Ionics Iberica,
S.A., owns and operates a 5.5 million gallon per day capacity
brackish water EDR facility and a 3.6 million gallon per day RO
seawater facility on Grand Canary Island, Spain.  Under long-term
contracts, the Company is selling the desalted water from both
facilities to the local water utility for distribution.

     The Company's wholly owned subsidiary, Ionics (Bermuda)
Ltd., owns and operates a 600,000 gallon per day EDR brackish
water desalting plant on the island of Bermuda.  This plant
supplies fresh water under a long-term contract with Watlington
Waterworks Ltd., a Bermuda corporation partially owned by Ionics.







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                               I-5



     Through its Ionics Aqua Design subsidiaries, the Company
owns and operates approximately 35 desalination plants on a
number of Caribbean islands, which provide drinking water to
hotels, resorts and governmental entities.  Drinking water on
these islands is usually supplied pursuant to water supply
contracts with terms ranging from five to ten years.

     6.    Chemical Supply

     In the chemical supply area, the Company uses its CloromatR
electrolytic membrane-based technology to produce sodium
hypochlorite and related chlor-alkali chemicals for industrial,
commercial and other non-consumer applications.  The Company's
wholly owned Australian subsidiary, Elite Chemicals Pty. Ltd.
(Elite), utilizes Cloromat systems to produce sodium hypochlorite
on-site in Brisbane for the industrial, commercial and janitorial
supply of bleach products, and to supply sodium hypochlorite to
treat the City of Brisbane's drinking water supply under a five-
year contract.  Elite has recently expanded its distribution of
bleach products to the Sydney area.

     The Company also supplies sodium hypochlorite for industrial
and commercial uses in the northeastern United States from its
manufacturing facility in Ludlow, Massachusetts, which contains a
Cloromat installation.

     7.    Food Processing

     Under an agreement with a major U.S. dairy cooperative, the
Company oversees whey processing activities at two plants owned
by the cooperative, and receives a processing fee based on the
production of demineralized whey for its services.  Included in
the equipment being utilized by the Company at these plants are
its ElectromatR electrodialysis systems.

     In July 1996, the Company acquired Separation Technology,
Inc. (STI), a supplier of membrane-based purification equipment
and services to the food industry based in St. Paul, MN.  Systems
built by STI are used primarily for the concentration,
clarification or fractionation of fluid food products or food
plant effluents.

Consumer Products

     The Company's Consumer Products business segment accounted
for approximately 21% of the Company's revenues in 1997.  The
Company's consumer products serve the bottled water, home water
purification and consumer bleach product market areas.




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                               I-6



     8. Aqua CoolR Pure Bottled Water

     Ionics entered the bottled water business in 1984.  The
Company's strategy is to utilize its proprietary desalination and
purification technology to produce a brand of drinking water,
named Aqua Cool Pure Bottled Water, which can be  reproduced with
uniform consistency and high quality at numerous locations around
the world.  Distribution operations have been established to
serve the areas in and around London, Manchester, Birmingham,
Bristol, Leeds, Newcastle and Southampton, England; a number of
metropolitan areas in the eastern, southeastern and central
United States; and, through joint ventures, in Bahrain, Kuwait
and Saudi Arabia.  The Company's business focuses on the sale of
Aqua Cool in five-gallon bottles to a variety of commercial and
residential customers.

     At the end of 1997, there were a total of 29 Aqua Cool
distribution centers in the United States and overseas, supplied
with Aqua Cool by eight regional water purification and bottling
facilities, supplying a customer base of approximately 120,000.

     9.    Home Water Purification Systems

           Point-of-Use Devices

     The Company participates in the "point-of-use" market for
over- and under-the-sink water purifiers through the manufacture
and sale of HYgeneR, a proprietary, EPA-registered, silver-
impregnated activated carbon filtering medium, and through the
sale of reverse osmosis and activated carbon-based filtering
devices.  The Company incorporates HYgene, which is designed to
prevent bacterial build-up while providing the capability of
removing undesirable tastes and odors from the water supply, into
its own bacteriostatic water conditioners and also sells HYgene
to manufacturers of household point-of-use water filters.

           Point-of-Entry Devices

     Ionics' point-of-entry water products include ion-exchange
water conditioners to "soften" hard water, and chemicals and
media for filtration and treatment.  The Company sells its
products, under the General Ionics and other brand names, through
both independent distributorships and wholly owned sales and
service dealerships.

     10.   Bleach-Based Consumer Products

     The Company's Elite New England division operates a Cloromat
facility to produce and distribute bleach-based products for the
consumer market, primarily one-gallon bleach products under
private label or under the Company's own "EliteR", "Super
ValueTM" and "UltraPureTM" brands, and methanol-based automobile
windshield wash solution.  These operations are conducted in a
129,000 square foot manufacturing facility located in Ludlow,
Massachusetts.

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                               I-7




Raw Materials and Sources of Supply

     All raw materials essential to the business of the Company
can normally be obtained from more than one source.  In those few
instances where raw materials are being supplied by only one
source, the current supplier has given the Company a lead time
for cancellation, which the Company believes is sufficient to
enable it to obtain other suppliers.  In addition, the Company
maintains inventories of single source items which it believes
are adequate under the circumstances.

     The Company produces the membranes required for its
equipment and systems that use the ED, EDR, MF, UF and EDI
processes.  In 1997, the Company started to produce RO membranes.
Membranes used for the RO process are also purchased from outside
suppliers, and are normally available from multiple sources.

Patents and Trademarks

     The Company believes that its products, know-how, servicing
network and marketing skills are more significant to its business
than trademarks or patent protection of its technology.
Nevertheless, the Company has a policy of applying for patents
both in the United States and abroad on inventions made in the
course of its research and development work for which a
commercial use is considered likely.  The Company owns numerous
United States and foreign patents and trademarks and has issued
licenses thereunder, and currently has additional pending patent
applications.  Of the approximately 100 outstanding U.S. patents
held by the Company, a substantial portion involves membranes,
membrane technology and related separations processes such as
electrodialysis and electrodialysis reversal, reverse osmosis,
ultrafiltration and electrodeionization.  The Company does not
believe that any of its individual patents or groups of related
patents, nor any of its trademarks, is of sufficient importance
that its termination or abandonment, or the cancellation of
licenses extending rights thereunder, would have a material
adverse effect on the Company.

Seasonality

     The activities of the Company's businesses are not of a
seasonal nature, other than certain activities of the Consumer
Products segment.  Bottled water sales and bleach products for
swimming pool use tend to increase during the summer months.
Also, sales levels for automobile windshield wash solution
increase in the winter months.








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Customers

     The nature of the Company's business is such that it
frequently has in progress large contracts with one or more
customers for specific projects; however, there is no one
customer whose purchases account for 10% or more of the Company's
consolidated revenues and whose loss would have a material
adverse effect on the Company and its subsidiaries taken as a
whole.

Backlog

     The Company's backlog of firm orders was $153,679,000 at
December 31, 1997 and $210,505,000 at December 31, 1996.  For
multi-year contracts, the Company includes in reported backlog
the revenues associated with the first five years of the
contract.  For multi-year contracts which are not otherwise
included in backlog, the Company includes in backlog up to one
year of revenues.  Ionics expects to fill approximately 77% of
its December 31, 1997 backlog during 1998.  The Company does not
believe that there are any seasonal aspects to these backlog
figures.

Government Contracts

     The Company does not believe that any of its sales under
U.S. Government contracts or subcontracts during 1997 are subject
to renegotiation.  The Company has not had adjustments to its
negotiated contract prices, nor are any proceedings pending for
such adjustments.

Research and Development

     Since the development of the ion exchange membrane and the
EDR process, Ionics has continued its commitment to research and
development directed toward products for use in water
purification, processing and measurement, and separations
technology.  The Company's research and development expenses were
approximately $5,410,000 in 1997, $5,108,000 in 1996, and
$4,180,000 in 1995.

Competition

     The Company experiences competition from a variety of
sources with respect to virtually all of its products, systems
and services, although the Company knows of no single entity that
competes with it across the full range of its products and
services.  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.





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                               I-9



     With respect to the Company's Membranes and Related
Equipment business segment, 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.  The Company has
numerous competitors in its conventional water treatment,
instruments and fabricated products business lines.

     In 1996, the International Desalination Association released
a report providing data regarding the manufacturers of
desalination equipment.  According to the report, which covered
land-based water desalination plants delivered or under
construction as of December 1995, with a capacity to produce 100
cubic meters (approximately 25,000 gallons) or more of fresh
water daily, Ionics ranked first in terms of the cumulative
number of such plants sold, having sold 1,414 plants of such
capacity, more than the next three manufacturers combined.  When
compared only to manufacturers of membrane-type desalination
equipment, Ionics ranked first in both number of units sold and
the total capacity of units sold.

     With respect to the Water, Food and Chemical Supply business
segment, the Company competes with suppliers of ultrapure water
services on a national and regional basis, and with other
manufacturers of membrane-related equipment.  In the chemical
supply activity, the Company competes with manufacturers and
distributors of sodium hypochlorite and water treatment
chemicals.

     With respect to the Company's Consumer Products business
segment, there are numerous bottled water companies which compete
with the Company, including several which are much larger than
the Company.  Most of the Company's competitors in point-of-entry
and point-of-use products for the home are small assemblers,
serving local or regional markets.  However, there are also
several large companies competing nationally in these markets.
In the case of its silver-impregnated activated carbon product
lines, the Company knows of two competitors with which it
competes on a national basis.

     The Company competes with many suppliers of bleach and
bleach-based cleaning products and automobile windshield wash for
the consumer market, a number of which are much larger 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.






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Environmental Matters

     Continued compliance by the Company and its subsidiaries
with federal, state and local provisions regulating the discharge
of materials into the environment or otherwise relating to the
protection of the environment is expected to have no material
effect upon capital expenditures, earnings or the competitive
position of the Company or any of its subsidiaries.

     The Company is one of approximately 1,000 potentially
responsible parties (PRPs) at a Superfund site at Solvent
Recovery Services of New England in Southington, Connecticut (the
"SRS Site").  The Company's volumetric ranking in comparison to
the total volume of wastes treated at the SRS Site is
approximately 0.5%.  A non-time critical removal action,
consisting of containment, pumping, and treatment of the most
heavily contaminated non-bedrock groundwater, was completed in
1995.  The Company's share of combined assessments to date
against all PRPs for non-time critical removal actions and other
work totals approximately $55,000.  The ultimate site cleanup
cost is currently not expected to exceed $59 million, of which
the Company's share would not exceed $308,000 including the
amounts already assessed against the Company.  While it is too
soon to predict the scope and cost of the final clean-up remedy
that the EPA will select, based on the Company's small volumetric
ranking and the identities of the larger PRPs, which include many
substantial companies, the Company believes that its liability in
this matter will not have a material effect on the Company or its
financial position.

During 1995, the Company acquired certain real property in
Maryland to accommodate expansion of the Elite bleach-based
consumer chemicals business.  Prior to its acquisition by the
Company, the property had been determined to have some
contamination of soil and groundwater.  In conjunction with the
purchase, the Company worked closely with the Maryland Department
of the Environment and, based upon an environmental study
completed by a third party consultant, reached a preliminary
agreement regarding treatment.  Based upon the costs of treatment
identified by the consultant, the Company has provided a
conservative accrual, recorded as part of the cost of the
property.  The Company believes that additional liability
associated with treatment of the property, if any, will not have
a material effect on the Company or its financial condition.

     The Company has never had a product liability claim grounded
in environmental liability, and believes that the nature of its
products and business makes such a claim unlikely.





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                              I-11



Employees

     The Company and its consolidated subsidiaries employ
approximately 2,000 full-time persons, none of whom are
represented by unions except for the employees of the Company's
Australian subsidiary and certain employees of the Company's
Spanish subsidiary.  The Company considers its relations with its
employees to be good.

Foreign Operations

     The Company's sales to customers in foreign countries
primarily involve desalination systems, water and wastewater
treatment systems, sodium hypochlorite, Cloromat systems,
products and services related to these foregoing systems, and
bottled water.  The Company seeks to minimize financial risks
relating to its international operations.  Wherever possible, the
Company obtains letters of credit or similar payment assurances
denominated in U.S. dollars.  If U.S. dollar payments cannot be
secured, the Company, where appropriate, enters into foreign
currency hedging transactions.  The Company also uses foreign
sources for equipment parts and may borrow funds in local
(foreign) currencies to offset the asset risk of foreign currency
devaluation.  Net foreign currency transaction gains included in
income before taxes totalled $100,000 in 1997, $548,000 in 1996
and $58,000 in 1995.

     Ionics engages in certain foreign operations both directly
and through the following wholly owned subsidiaries:  Ionics
(Bermuda) Ltd.; Ionics Iberica, S.A.; Ionics (U.K.) Limited;
Ionics Italba, S.p.A.; Ionics Nederland B.V.; Global Water
Services, S.A.; Elite Chemicals Pty. Ltd.; Eau et Industrie;
Resources Conservation Co. International; Ionics (Korea) Ltd.;
Aqua Design, Inc., subsidiaries and affiliates; Ionics Asia-
Pacific Pte Ltd.; Ionics Watertec Pty. Ltd. and Ionics Foreign
Sales Corporation Limited.  In 1997, Ionics acquired a 55%
ownership interest in Enersave Engineering Systems Sdn Bhd, a
Malaysian corporation with subsidiary operations in Indonesia and
China ("Enersave").

     The Company engages in various foreign operations through
investments in affiliated companies and joint venture
relationships.  The activities include the production, sale and
distribution of bottled water through a 40% owned affiliate in
Bahrain, a 40% owned affiliate in Saudi Arabia, and a 49% owned
affiliate in Kuwait.

  In addition, the Company has a 19% ownership interest in
Watlington Waterworks Ltd. in Bermuda.  Watlington collects,
treats and distributes water throughout Bermuda for both potable
and non-potable uses.  The Company also has a 50% ownership
interest in Yuasa-Ionics Co., Ltd., Tokyo, Japan, which among its
activities serves as a distributor of certain of the Company's
products in Japan; a 49% ownership interest in



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                              I-12



Ionics-Mega s.r.o., a limited liability company of the Czech
Republic established to pursue water treatment opportunities in
that country; and, through Ionics Iberica, S.A., 20% interests in
Aguas Tratadas de Cadereyta, S.A. de C.V. and Aguas Tratadas de
Madero, S.A. de C.V., companies organized to provide water
treatment services in Mexico.

     Further geographical and financial information concerning
the Company's foreign operations appears in Notes 1, 5, 8, 9, 13,
14 and 15 to the Company's Consolidated Financial Statements
included as part of the Company's 1997 Annual Report to
Stockholders, which Notes are incorporated herein by reference.

Financial Information About Foreign and
Domestic Operations and Export Sales

     The information contained in Note 15 of Notes to
Consolidated Financial Statements contained in the Company's
Annual Report to Stockholders for the year ended December 31,
1997 is incorporated herein by reference.

Item 2.  PROPERTIES

     The Company owns or leases and occupies various
manufacturing and office facilities in the United States and
abroad.  The principal facilities owned by the Company include
two buildings in Watertown, Massachusetts, containing
approximately 250,000 square feet and housing executive offices,
laboratories and manufacturing and assembly operations; a 234,000
square foot facility in Elkton, Maryland which is utilized
primarily for consumer bleach and automobile windshield wash
product distribution; a 129,000 square foot facility in Ludlow,
Massachusetts which is utilized primarily for packaging and
distribution of consumer bleach and windshield wash products; two
buildings in Bridgeville, Pennsylvania containing approximately
77,000 square feet and housing manufacturing operations for home
water treatment equipment and fabricated products; and other
facilities in the U.S. and overseas for various operations
relating to the business of the Company.

     The Company makes use primarily of leased facilities for its
Aqua Cool bottled water distribution centers at 29 locations in
the U.S. and overseas.  The majority of these facilities contain
less than 10,000 square feet.

     The Company considers the business facilities that it
utilizes to be adequate for the uses to which they are being put.









/15


                              I-13




Item 3.  LEGAL PROCEEDINGS

     The Company is involved in the normal course of its business
in various litigation matters.  Although the Company is unable to
determine at the present time whether it will have any liability
in any of the pending matters, some of which are in the early
stages of pre-trial discovery, the Company believes generally
that it has meritorious defenses and that none of the pending
matters will have an outcome material to the financial condition
or business of the Company.

     On September 3, 1997, the Company was served with a third-
party complaint by Sybron Chemicals, Inc. ("Sybron") and a Sybron
employee, Michael Moldofsky ("Moldofsky"), in connection with
litigation pending in the District Court for Dallas County,
Texas, 44th Judicial District, entitled SGS-Thomson
Microelectronics, Inc. v. Sybron Chemicals, Inc. and Michael
Moldofsky.  In the pending litigation, the plaintiff, SGS-Thomson
Microelectronics, Inc. ("S-T"), alleges that defendants Sybron
and Moldofsky caused S-T to incur damages of at least $24 million
as a result of allegedly defective ion-exchange resin
manufactured and sold to it by Sybron for use in an S-T ultrapure
water facility serving one of its semiconductor plants.  In the
third-party complaint filed against the Company, the defendants
Sybron and Moldofsky allege that in the event they are found
liable to S-T, the Company may be liable to them for all or part
of S-T's alleged damages.  The Company installed the resin in
question into deionized water vessels under a $3,500 contract
with S-T.  The Company disputes all material allegations made
against it in the third-party complaint and believes that it
properly performed its services for S-T.  S-T did not bring suit
against the Company.  The Company intends to defend itself
vigorously in this litigation, which is in the early discovery
stages.

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

     No matters were submitted to a vote of security holders
during the fourth quarter of the fiscal year covered by this
report.
















/16

                              I-14



                             PART II


Item 5.  MARKET FOR REGISTRANT'S COMMON EQUITY AND
         RELATED STOCKHOLDER MATTERS

     Reference is made to the Company's Annual Report to
Stockholders for the year ended December 31, 1997.  The
information set forth on page 35 entitled "Common Stock Price
Range" and on the inside back cover of such Annual Report is
hereby incorporated by reference.


Item 6.  SELECTED FINANCIAL DATA

    Reference is made to the Company's Annual Report to Stockholders
for the year ended December 31, 1997.  The information set forth on
page 35 of such Annual Report entitled "Statement of Operations
Data" and "Balance Sheet Data" is hereby incorporated by reference.


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

    Reference is made to the Company's Annual Report to Stockholders
for the year ended December 31, 1997.  The information set forth on
pages 17 through 19 of such Annual Report entitled "Management's
Discussion and Analysis of Results of Operations and Financial
Condition" is hereby incorporated by reference.


Item 7A.  QUANTITATIVE AND QUALITATIVE DISCLOSURE ABOUT MARKET RISK

    This item is not yet applicable to the Company.


Item 8.  FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

    Reference is made to the Company's Annual Report to Stockholders
for the year ended December 31, 1997.  The consolidated balance
sheets of the Registrant as of December 31, 1997 and 1996, the
related consolidated statements of operations, cash flows and
stockholders' equity for the years ended December 31, 1997, 1996 and
1995, and the related notes with the opinion thereon of Coopers &
Lybrand L.L.P., independent accountants, on pages 19 through 34, and
Selected Quarterly Financial Data (unaudited) on page 35, are hereby
incorporated by reference.


Item 9.  CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON
        ACCOUNTING AND FINANCIAL DISCLOSURE

    This item is not applicable to the Company.



/17

                              II-1



                             PART III

Item 10.  DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

    The information required by Item 10 with respect to directors is
hereby incorporated by reference from the Company's definitive proxy
statement for the Annual Meeting of Stockholders to be held May 7,
1998 to be filed with the Securities and Exchange Commission on or
about March 30, 1998.

    The information regarding executive officers is as follows:
<TABLE>
<CAPTION>
                      Age as of     Positions
Name                 March 1, 1998  Presently Held
<S>                       <C>       <C>
Arthur L. Goldstein*      62        President, Chief Executive Officer
                                     and Director since 1971; Chairman
                                     of the Board since 1990
William E. Katz           73        Executive Vice President since 1983;
                                     Director since 1961
Robert J. Halliday        43        Vice President, Finance since
                                     December 1990; Chief Financial
                                     Officer since August 1992
Stephen Korn              52        Vice President, General Counsel
                                     and Clerk since September 1989
Theodore G. Papastavros   64        Vice President since 1975;
                                     Vice President, Strategic Planning
                                     since February 1990; Treasurer from
                                     February 1990 until November 1997
A. Ernest Whiton          36        Vice President and Corporate Controller
                                     since November 14, 1997
___________________
* Member of Executive Committee
</TABLE>
     There are no family relationships between any of the
officers or directors.  Officers of the Company are elected each
year at the annual meeting of Directors.

     Except for Mr. Whiton, all of the above executive officers
have been employed by the Company in various capacities for more
than five years.  Prior to joining the Company, Mr. Whiton served
as an audit manager with Price Waterhouse, Boston, Massachusetts.

Item 11.  EXECUTIVE COMPENSATION

     The information required by Item 11 is hereby incorporated
by reference from the Company's definitive proxy statement for
the Annual Meeting of Stockholders to be held May 7, 1998 to be
filed with the Securities and Exchange Commission on or about
March 30, 1998.







/18

                               III-1




Item 12.  SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS
          AND MANAGEMENT

     The information required by Item 12 is hereby incorporated
by reference from the Company's definitive proxy statement for
the Annual Meeting of Stockholders to be held May 7, 1998 to be
filed with the Securities and Exchange Commission on or about
March 30, 1998.


Item 13.  CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

     The information required by Item 13 is hereby incorporated
by reference from the Company's definitive proxy statement for
the Annual Meeting of Stockholders to be held May 7, 1998 to be
filed with the Securities and Exchange Commission on or about
March 30, 1998.







































/19

                               III-2



                            PART IV

Item 14.  EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND
          REPORTS ON FORM 8-K

(a)  1.   Financial Statements

          See Index to Financial Statements and Financial
          Statement Schedules on page IV-7.  The Financial
          Statement Schedules are filed as part of this Annual
          Report on Form 10-K.

     2.   Financial Statement Schedules

          See Index to Financial Statements and Financial
          Statement Schedules on page IV-7.
<TABLE>
<CAPTION>
     3.   Exhibits

     Exhibit
       No.    Description
     <S>      <C>                                                         <C>
     3.0      Articles of Organization and By-Laws

              3.1    Restated Articles of Organization filed
                     April 16, 1986.

              3.1(a) Amendment to the Restated Articles of
                     Organization filed June 19, 1987.

              3.1(b) Amendment to Restated Articles of                      *
                     Organization filed May 13, 1988
                     (filed as Exhibit 3.1(b) to
                     Registration Statement No. 33-38290 on
                     Form S-2 effective January 24, 1991).

              3.1(c) Amendment to Restated Articles of                      *
                     Organization filed May 8, 1992
                     (filed as Exhibit 3.1 to Form 10-Q
                     for quarterly period ending
                     June 30, 1996).

              3.2    By-Laws, as amended through November 14, 1997.

     4.0      Instruments defining the rights of security holders,
              including indentures

              4.1    Renewed Rights Agreement, dated as of                  *
                     August 19, 1997 between Registrant and
                     BankBoston N.A. (filed as Exhibit 1 to
                     Registrant's Current Report on Form 8-K
                     dated August 27, 1997).




/20


                             IV-1




              4.2     Form of Common Stock Certificate

     10.      Material Contracts

              10.1    1979 Stock Option Plan, as amended through           *
                      February 22, 1996 (filed as Exhibit 10.1 to
                      Registrant's Annual Report on Form 10-K for the
                      year ended December 31, 1995).

              10.2    1986 Stock Option Plan for Non-Employee Directors,   *
                      as amended through February 19, 1997 (filed as
                      Exhibit 10.2 to Registrant's Annual Report on
                      Form 10-K for the year ended December 31, 1996).

              10.3    Amended and Restated Credit Agreement between
                      Registrant and the First National Bank of Boston
                      dated as of December 31, 1992.

              10.3(1) Amendment Agreement No. 1, dated as of               *
                      December 31, 1995, to Amended and Restated
                      Credit Agreement between Registrant and The
                      First National Bank of Boston (filed as Exhibit
                      10.3(1) to Registrant's Annual Report on Form 10-K
                      for the year ended December 31, 1995).

              10.4    Operating Agreement dated as of September 27,
                      1989 between Registrant and Aqua Cool
                      Enterprises, Inc.

              10.5    Term Lease Master Agreement dated as of
                      September 27, 1989 between Registrant and
                      Aqua Cool Enterprises, Inc.

              10.6    Option Agreement dated as of September 27, 1989      *
                      among Registrant, Aqua Cool Enterprises, Inc.
                      and the other parties named therein (filed as
                      Exhibit 10.6 to Registrant's registration
                      statement on Form S-2, No. 33-38290,
                      effective January 24, 1991).

              10.7    1994 Restricted Stock Plan (filed as Exhibit 10.12   *
                      to Registrant's Annual Report on Form 10-K dated
                      March 30, 1995).

              10.8    1997 Stock Incentive Plan (filed as Exhibit 10.12    *
                      to Registrant's Annual Report on Form 10-K dated
                      December 31, 1996).

              10.9    Ionics, Incorporated Supplemental Executive
                      Retirement Plan effective as of January 1, 1996.

              10.10   Form of Employee Retention Agreement dated
                      February 24, 1998 between the Registrant and
                      each of its executive officers and certain other
                      officers of Registrant and its subsidiaries.


/21


                             IV-2





     13.      Annual Report to Stockholders of the Registrant for
              the year ended December 31, 1997 (only pages 17
              through 36 and the inside back cover constitute an
              exhibit to this report).

     21.      Subsidiaries of the Registrant.

     23.      Consents

              23.1   Consent of Coopers & Lybrand L.L.P. to incorporation
                     by reference of that firm's report dated
                     February 17, 1998, which is included on page 19 of
                     the Registrant's Annual Report to Stockholders
                     for the year ended December 31, 1997.

     24.      Power of Attorney.

     27.      Financial Data Schedule.                                     **
         27.1 Financial Data Schedule - Restated                           **
         27.2 Financial Data Schedule - Restated                           **
         27.3 Financial Data Schedule - Restated                           **
         27.4 Financial Data Schedule - Restated                           **
         27.5 Financial Data Schedule - Restated                           **
         27.6 Financial Data Schedule - Restated                           **
         27.7 Financial Data Schedule - Restated                           **
         27.8 Financial Data Schedule - Restated                           **

________________________________
     *   incorporated herein by reference
     **  for electronic purposes only



</TABLE>





















/22


                             IV-3





(b)  Reports on Form 8-K

     No reports on Form 8-K were filed by the Registrant during
     the last quarter of fiscal 1997.

     Undertaking

     For purposes of complying with the amendments to the rules
     governing Form S-8 effective July 13, 1990 under the
     Securities Act of 1933, the undersigned hereby undertakes as
     follows, which undertaking shall be incorporated by
     reference into Registrant's registration statements on Form
     S-8 Nos. 33-14194, 33-5814, 33-2092, 2-72936, 2-82780, 2-
     64255, 33-41598, 33-54293, 33-59051, 333-05225, 333-29135,
     and 33-54400.

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




















/23


                             IV-4




                        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.

                             IONICS, INCORPORATED
                             (Registrant)



                             By/s/Arthur L. Goldstein
                                  Arthur L. Goldstein,
                                  Chairman of the Board,
                                  President and Chief
                                  Executive Officer

                             Date:    March 27, 1998



     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.



Date: March 27, 1998         By/s/Arthur L. Goldstein
                                  Arthur L. Goldstein,
                                  Chairman of the Board,
                                  President and
                                  Chief Executive Officer
                                  (principal executive
                                   officer) and Director


Date: March 27, 1998         By/s/Robert J. Halliday
                                  Robert J. Halliday,
                                  Vice President, Finance
                                  and Chief Financial
                                  Officer (principal
                                  financial officer)


Date: March 27, 1998         By/s/A. Ernest Whiton
                                  A. Ernest Whiton,
                                  Vice President and
                                  Corporate Controller
                                  (principal accounting
                                   officer)




/24


                             IV-5











Date: March 27, 1998         By/s/Douglas R. Brown
                                  Douglas R. Brown, Director


Date: March 27, 1998         By/s/William L. Brown
                                  William L. Brown, Director


Date: March 27, 1998         By/s/Arnaud de Vitry d'Avaucourt
                                  Arnaud de Vitry d'Avaucourt,
                                  Director


Date: March 27, 1998         By/s/Kathleen F. Feldstein
                                  Kathleen F. Feldstein,
                                  Director


Date: March 27, 1998         By/s/William E. Katz
                                  William E. Katz, Director


Date: March 27, 1998         By/s/Robert B. Luick
                                  Robert B. Luick, Director


Date: March 27, 1998         By/s/John J. Shields
                                  John J. Shields, Director


Date: March 27, 1998         By/s/Carl S. Sloane
                                  Carl S. Sloane, Director


Date: March 27, 1998         By/s/Daniel I.C. Wang
                                  Daniel I.C. Wang, Director


DATE: March 27, 1998         By/s/Mark S. Wrighton
                                  Mark S. Wrighton, Director


Date: March 27, 1998         By/s/Allen S. Wyett
                                  Allen S. Wyett, Director






/25


                             IV-6




                     IONICS, INCORPORATED
INDEX TO FINANCIAL STATEMENTS AND FINANCIAL STATEMENT SCHEDULES

                                                         PAGES

Report of Independent Accountants                           19*

Financial Statements:

     Consolidated Statements of Operations for the
     Years Ended December 31, 1997, 1996 and 1995           20*

     Consolidated Balance Sheets as of
     December 31, 1997 and 1996                             21*

     Consolidated Statements of Cash Flows for the
     Years Ended December 31, 1997, 1996 and 1995           22*

     Consolidated Statements of Stockholders' Equity for
     the Years Ended December 31, 1997, 1996 and 1995       23*

     Notes to Consolidated Financial Statements          24-34*


Supporting Financial Statement Schedules for the years ended
December 31, 1997, 1996 and 1995:

     Schedule II - Valuation and Qualifying Accounts     IV-8


Report of Independent Accountants on Financial
Statement Schedule                                       IV-9

__________________

All other schedules are omitted because the amounts are
immaterial, the schedules are not applicable, or the required
information is shown in the financial statements or the notes
thereto.

*  Page references are to the Annual Report to Stockholders of
   the Company for the year ended December 31, 1997, which pages
   are incorporated herein by reference.














/26


                             IV-7



<TABLE>
<CAPTION>
                             IONICS, INCORPORATED

                SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS



                                      Additions    Additions
                         Balance at   Charged to     Due to
                           End of     Costs and     Acquired                      Balance at
Description              Prior Year    Expenses    Businesses     Deductions(A)   End of Year
<S>                      <C>          <C>          <C>            <C>             <C>
Allowance for doubtful
accounts and uncollectible
notes receivable:

     Years ended:

     December 31, 1997   $2,858,000   $1,408,000   $  40,000      $2,017,000      $2,289,000

     December 31, 1996   $2,410,000   $1,011,000   $ 286,000      $  849,000      $2,858,000

     December 31, 1995   $2,197,000   $  579,000   $  21,000      $  387,000      $2,410,000


(A)  Deductions result primarily from the write-off of accounts.






</TABLE>
























/27


                             IV-8





               REPORT OF INDEPENDENT ACCOUNTANTS


To the Board of Directors and Stockholders of
Ionics, Incorporated:

     Our report on the consolidated financial statements of
Ionics, Incorporated as of December 31, 1997 and 1996 and for
each of the three years in the period ended December 31, 1997
has been incorporated by reference in this Form 10-K from page
19 of the 1997 Annual Report to Stockholders of Ionics,
Incorporated.  In connection with our audits of such financial
statements, we have also audited the related financial statement
schedule for each of the three years in the period ending
December 31, 1997, listed in the Index on page IV-7 of this Form
10-K.

     In our opinion, the financial statement schedule referred
to above, when considered in relation to the basic financial
statements taken as a whole, present fairly, in all material
respects, the information required to be included therein.



                                       /s/COOPERS & LYBRAND L.L.P.



Boston, Massachusetts
February 17, 1998

























/28


                             IV-9



<TABLE>
<CAPTION>
                                  EXHIBIT INDEX

                                                                     Sequentially
     Exhibit                                                           Numbered
       No.      Description                                              Page
     <S>      <C>                                                        <C>
     3.0      Articles of Organization and By-Laws

              3.1     Restated Articles of Organization filed             32
                      April 16, 1986.

              3.1(a)  Amendment to the Restated Articles of               39
                      Organization filed June 13, 1987.

              3.1(b)  Amendment to Restated Articles of                    *
                      Organization filed May 13, 1988
                      (filed as Exhibit 3.1(b) to
                      Registration Statement No. 33-38290 on
                      Form S-2 effective January 24, 1991).

              3.1(c)  Amendment to Restated Articles of                    *
                      Organization filed May 8, 1992
                      (filed as Exhibit 3.1 to Form 10-Q
                      for quarterly period ending
                      June 30, 1996).

              3.2     By-Laws, as amended through                         42
                      November 14, 1997.

     4.0      Instruments defining the rights of security holders,
              including indentures

              4.1     Renewed Rights Agreement, dated as of                *
                      August 19, 1997 between Registrant and
                      BankBoston N.A. (filed as Exhibit 1 to
                      Registrant's Current Report on Form 8-K
                      dated August 27, 1997).

              4.2     Form of Common Stock Certificate                    61

     10.      Material Contracts

              10.1    1979 Stock Option Plan, as amended through          *
                      February 22, 1996 (filed as Exhibit 10.1 to
                      Registrant's Annual Report on Form 10-K for the
                      year ended December 31, 1995).

              10.2    1986 Stock Option Plan for Non-Employee Directors,  *
                      as amended through February 19, 1997 (filed as
                      Exhibit 10.2 to Registrant's Annual Report on
                      Form 10-K for the year ended December 31, 1996).

              10.3    Amended and Restated Credit Agreement between       64
                      Registrant and the First National Bank of Boston
                      dated as of December 31, 1992.

/29





              10.3(1) Amendment Agreement No. 1, dated as of              *
                      December 31, 1995, to Amended and Restated
                      Credit Agreement between Registrant and The
                      First National Bank of Boston (filed as Exhibit
                      10.3(1) to Registrant's Annual Report on Form 10-K
                      for the year ended December 31, 1995).

              10.4    Operating Agreement dated as of September 27,      118
                      1989 between Registrant and Aqua Cool
                      Enterprises, Inc.

              10.5    Term Lease Master Agreement dated as of            140
                      September 27, 1989 between Registrant and
                      Aqua Cool Enterprises, Inc.

              10.6    Option Agreement dated as of September 27, 1989     *
                      among Registrant, Aqua Cool Enterprises, Inc.
                      and the other parties named therein (filed as
                      Exhibit 10.6 to Registrant's registration
                      statement on Form S-2, No. 33-38290,
                      effective January 24, 1991).

              10.7    1994 Restricted Stock Plan (filed as Exhibit 10.12  *
                      to Registrant's Annual Report on Form 10-K dated
                      March 30, 1995).

              10.8    1997 Stock Incentive Plan (filed as Exhibit 10.12   *
                      to Registrant's Annual Report on Form 10-K dated
                      December 31, 1996).

              10.9    Ionics, Incorporated Supplemental Executive        155
                      Retirement Plan effective as of January 1, 1996.

              10.10   Form of Employee Retention Agreement dated         165
                      February 24, 1998 between the Registrant and
                      each of its executive officers and certain other
                      officers of Registrant and its subsidiaries.

     13.      Annual Report to Stockholders of the Registrant for        177
              the year ended December 31, 1997 (only pages 17
              through 36 and the inside back cover constitute an
              exhibit to this report).

     21.      Subsidiaries of the Registrant.                            213

     23.      Consents

              23.1    Consent of Coopers & Lybrand L.L.P. to             214
                      incorporation by reference of that firm's
                      report dated February 17, 1998, which is
                      included on page 19 of the Registrant's Annual
                      Report to Stockholders for the year ended
                      December 31, 1997.



/30





     24.      Power of Attorney.                                         215

     27.      Financial Data Schedule.                                    **
         27.1 Financial Data Schedule - Restated                          **
         27.2 Financial Data Schedule - Restated                          **
         27.3 Financial Data Schedule - Restated                          **
         27.4 Financial Data Schedule - Restated                          **
         27.5 Financial Data Schedule - Restated                          **
         27.6 Financial Data Schedule - Restated                          **
         27.7 Financial Data Schedule - Restated                          **
         27.8 Financial Data Schedule - Restated                          **
________________________________
     *   incorporated herein by reference
     **  for electronic purposes only
</TABLE>









































/31