SECURITIES AND EXCHANGE COMMISSION
                                           WASHINGTON, DC 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 January 1, 2000

[   ] Transition Report Pursuant to Section 13 or 15(d) of the Securities
      Exchange Act of 1934

                                      Commission file number 1-12137

                                           THERMO FIBERGEN INC.
                          (Exact name of Registrant as specified in its charter)

Delaware                                         04-3311544
(State or other jurisdiction of
incorporation or organization)       (I.R.S. Employer Identification No.)

8 Alfred Circle
Bedford, Massachusetts                                             01730
(Address of principal executive offices)                        (Zip Code)

          Registrant's telephone number, including area code: (781) 622-1000

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

       Title of each class          Name of each exchange on which registered
Common Stock, $.01 par value                    American Stock Exchange
Redemption Rights

          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 the filing
requirements for at least 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 the Registrant's knowledge, in definitive proxy or information
statements incorporated by reference into Part III of this Form 10-K or any
amendment to this Form 10-K. [ ]

The aggregate market value of the voting stock held by nonaffiliates of the
Registrant as of January 28, 2000, was approximately $42,148,000.

As of January 28, 2000, the Registrant had 14,160,600 shares of Common Stock
outstanding.

                     DOCUMENTS INCORPORATED BY REFERENCE

Portions of the Registrant's Annual Report to Shareholders for the year ended
January 1, 2000, are incorporated by reference into Parts I and II.

Portions of the Registrant's definitive Proxy Statement for the Annual Meeting
of Shareholders to be held on May 18, 2000, are incorporated by reference into
Part III.

<PAGE>


                                     PART I

Item 1.  Business

(a)   General Development of Business

      Thermo Fibergen Inc. (the Company or the Registrant) operates in two
business segments: Fiber-recovery and Water-clarification Services and
Cellulose-based Products. The Fiber-recovery and Water-clarification Services
segment designs, builds, owns, and operates plants to help pulp and paper mills
improve product quality, reduce costs, and close the loop in their water and
solids systems on a long-term contract basis. The Company currently owns and
operates one such plant in South Carolina, which it began operating in July 1998
under a ten-year contract.

      The Cellulose-based Products segment includes the Company's GranTek
subsidiary, which employs patented technology to produce biodegradable absorbing
granules from papermaking byproducts that are marketed and sold as Biodac(R)
inert carriers for agricultural crop protection chemicals, Gran-sorb(TM) oil and
grease absorbents, PaPurr(TM) cat box fillers, and FiberRest(TM) animal bedding.
In addition, in October 1999, the Company established a subsidiary, NEXT Fiber
Products Inc., to develop, produce, and market fiber-based composites primarily
for the building industry. The Company is currently finalizing development of
the composites material and expects to complete construction of and begin
operating the composites manufacturing facility, located in Green Bay,
Wisconsin, during 2000.

      The Company was incorporated in Delaware in February 1996 as a wholly
owned subsidiary of Thermo Fibertek Inc. Thermo Fibertek is a 91%-owned
subsidiary of Thermo Electron Corporation. On January 31, 2000, Thermo Electron
announced that, as part of a major reorganization, it plans to spin off its
equity interest in Thermo Fibertek as a dividend to Thermo Electron
shareholders. Under the plan, the Company will remain a majority-owned
subsidiary of Thermo Fibertek.

      In September 1996, the Company sold 4,715,000 units, each unit consisting
of one share of Company common stock and one redemption right, in an initial
public offering at $12.75 per unit. The common stock and redemption rights
subsequently began trading separately. Holders of a redemption right have the
option to require the Company to redeem one share of Thermo Fibergen common
stock at $12.75 per share in September 2000 or September 2001, for a total
redemption value of $60,116,000. A redemption right may only be exercised if the
holder owns a share of Company common stock at that time. As of January 1, 2000,
there were 4,715,000 redemption rights outstanding and only 3,725,500 shares of
Company common stock held by persons other than Thermo Electron or Thermo
Fibertek. In addition, Thermo Electron, Thermo Fibertek, and/or the Company may
acquire additional shares of the Company's common stock in the open market, and
there can be no assurance that the Company will issue additional shares of its
common stock through the exercise of employee stock options or other
transactions. To the extent that the number of redemption rights exceeds the
number of shares of common stock held by persons other than Thermo Electron or
Thermo Fibertek, the Company will not be required to redeem the total redemption
value. The redemption rights are guaranteed, on a subordinated basis, by Thermo
Electron. As of January 1, 2000, Thermo Fibertek owned 10,419,350 shares of the
Company's common stock, representing 74% of such outstanding common stock. As of
January 1, 2000, Thermo Electron owned 15,750 shares of Company common stock,
representing 0.1% of such outstanding common stock.

      Thermo Fibertek develops, manufactures, and markets a range of equipment
and products for the pulp and paper recycling industries. Thermo Electron
develops, manufactures, and sells measurement and detection instruments used in
virtually every industry to monitor, collect, and analyze data that provide
knowledge for the user. For example, Thermo Electron's powerful analysis
technologies help researchers sift through data to unlock the mysteries of DNA
or develop new drugs; allow manufacturers to fabricate ever-smaller components
required to carry greater amounts of information, faster; or monitor and control
industrial processes on-line to ensure that critical quality standards are met
efficiently.

                                       2
<PAGE>

Forward-looking Statements

      Forward-looking statements, within the meaning of Section 21E of the
Securities Exchange Act of 1934, are made throughout this Annual Report on Form
10-K. For this purpose, any statements contained herein that are not statements
of historical fact may be deemed to be forward-looking statements. Without
limiting the foregoing, the words "believes," "anticipates," "plans," "expects,"
"seeks," "estimates," and similar expressions are intended to identify
forward-looking statements. There are a number of important factors that could
cause the results of the Company to differ materially from those indicated by
such forward-looking statements, including those detailed under the heading
"Forward-looking Statements" in the Registrant's 1999* Annual Report to
Shareholders, which statements are incorporated herein by reference.

(b)   Financial Information About Segments

      Financial information concerning the Company's segments is summarized in
Note 9 to Consolidated Financial Statements in the Registrant's 1999 Annual
Report to Shareholders, which information is incorporated herein by reference.

(c)   Description of Business

      (i)  Principal Products and Services

Fiber-recovery and Water-clarification Services

      Through its Fiber-recovery and Water-clarification Services segment, the
Company designs, builds, owns, and operates plants to help pulp and paper mills
improve product quality, reduce costs, and close the loop in their water and
solids systems on a long-term contract-basis. The Company currently owns and
operates one such plant in South Carolina, which it began operating in July 1998
under a ten-year contract. The Company's facility generally operates 24 hours a
day, seven days a week. The paper mill pumps its used process water directly
into the Company's system. The facility recovers and returns long fiber to the
mill and clarifies water, which is recycled for reuse in the papermaking
process. The paper mill pays the Company a monthly fee for these services.

Cellulose-based Products

      The Company's GranTek subsidiary employs patented technology to produce
biodegradable absorbing granules from papermaking byproducts that are marketed
and sold as Biodac(R) agricultural carriers, Gran-sorb(TM) oil and grease
absorbents, PaPurr(TM) (pronounced "paper") cat box filler, and FiberRest(TM)
animal bedding.

      Biodac(R) is used to deliver agricultural chemicals for professional turf,
home lawn and garden, agricultural row-crop, and mosquito-control applications.
Gran-sorb is currently being sold throughout the Midwest. PaPurr, which is
offered in conventional and clumping formulations as an alternative to clay, is
now available in more than 3,000 stores throughout the U.S. and Canada. The
Company is working to further expand distribution through mass merchandisers and
specialty pet stores. The Company's recently introduced FiberRest animal bedding
is a highly absorbent granular product made from paper fibers, clay, and lime.
FiberRest is available throughout Southern Ohio, North/Central Kentucky, and
Southeastern Indiana. Products under development include controlled-release
granules for carrying fertilizers.

      In October 1999, the Company formed a subsidiary, NEXT Fiber Products
Inc., to develop, produce, and market fiber-based composites. The Company is
currently finalizing development of fiber-based composite products and is
constructing a facility in Green Bay, Wisconsin, to manufacture such products.
--------------------
* References to 1999, 1998, and 1997 herein are for the fiscal years ended
  January 1, 2000, January 2, 1999, and January 3, 1998, respectively.


                                       3
<PAGE>

      (ii) and (xi) New Products; Research and Development

      The Company continues research and development efforts to develop
high-value products using materials recovered from papermaking byproducts,
including controlled-release granules for crop-protection chemicals and
fertilizers, as well as new, cellulose-fiber-based composites for plastic lumber
and other applications.

      The Company's mobile pilot plant is used to demonstrate its fiber-recovery
and water-clarification process, and to test the effluent streams of mills in
the United States and Canada. In addition, the GranTek subsidiary operates a
manufacturing plant in Green Bay, Wisconsin, at which it processes papermaking
byproducts provided by a nearby paper mill into cellulose-based granules. A
pilot plant is located within GranTek's main manufacturing plant. This pilot
plant processes up to 24 tons of material per day, and is used to develop many
of the innovations implemented in GranTek's main plant. The Company believes
that this pilot plant will provide the ability to process materials from other
paper mills under operating conditions and in quantities sufficient to determine
final product and operating characteristics and costs, as well as to develop new
products.

      The Company currently intends to limit the pace and amount of its research
and development so that its internally funded research and development
expenditures will not exceed the interest income earned on its cash, cash
equivalents, and available-for-sale investments, plus the Company's operating
earnings, if any, before research and development expenses.

      Research and development expenses for the Company were $1,385,000,
$1,454,000, and $1,877,000 in 1999, 1998, and 1997, respectively.

      (iii)         Raw Materials

      The raw material used in the manufacture of GranTek's cellulose-based
products is obtained from a single paper mill. The mill has the exclusive right
to supply papermaking byproducts to the Company's existing granulation plant in
Green Bay, Wisconsin, under a contract that expires in December 2001, subject to
successive mutual two-year extensions. Although the Company believes that its
relationship with the mill is good, no assurance can be given that the mill will
agree to renew the contract upon its termination. The inability of the Company
to obtain papermaking byproducts from this paper mill would have a material
adverse effect upon the Company's operations.

      During 1998, the Company entered into a five-year contract with a supplier
to purchase all necessary chemicals used in conjunction with certain equipment
for the processing of papermaking byproducts at its fiber-recovery and
water-clarification facility located in South Carolina. The contract expires in
July 2003.

      During 1998, the Company entered into a contract with a supplier to
purchase all natural gas requirements and natural gas management services that
are used by its GranTek subsidiary from the supplier through October 2000. The
Company has the option to enter into forward contracts with the supplier to
purchase specified quantities of natural gas at the then-current posted price
through specified future dates.

      (iv)          Patents, Licenses, and Trademarks

      The Company currently holds several U.S. patents, expiring at various
dates ranging from 2004 to 2016, relating to various aspects of the processing
of cellulose-based granular materials and the use of such materials in the
agricultural, professional turf, home lawn and garden, general absorption, oil
and grease absorption, and cat box filler markets. The Company also has foreign
counterparts to its U.S. patents in Canada and in various European countries,
and has additional patents pending in Canada and certain European countries.



                                       4
<PAGE>

      The Company has filed several U.S. patent applications for various
products and processes relating to papermaking byproducts and expects to file
additional patent applications in the future. In addition, Thermo Fibertek holds
two U.S. patents relating to the "scalping" technology, which is an important
component of the Company's fiber-recovery system, that expire in 2011 and 2014.
Although the Company has licensed the technology covered by Thermo Fibertek's
patents for use in pulp and paper industry applications, the Company does not
itself hold any patents or patent applications with respect to its
fiber-recovery and water-clarification system.

      The Company has granted a company a nonexclusive license under two of its
patents to sell cellulose-based granules produced at an existing site for sale
in the oil- and grease-absorption and cat box filler markets.

      (v)           Seasonal Influences

Fiber-recovery and Water-clarification Services

      Not applicable.

Cellulose-based Products

      Revenues from the Cellulose-based Products segment are principally from
sales in the agricultural-carrier market. The Company's primary customers in
this market, chemical formulators, typically purchase carriers during the winter
and spring for the cultivation and planting season. As a result, the Company
earns a disproportionately high share of its revenues from its
agricultural-carrier products during the first two quarters of the year. The
Company believes that its entrance into the oil and grease absorption, cat box
filler, animal bedding, and international agricultural row-crop markets, if
successful, may mitigate the seasonality of the Company's sales.

      (vi)          Working Capital Requirements

      There are no special inventory requirements or credit terms extended to
customers that would have a material adverse effect on the Company's working
capital.

      (vii)         Dependency on a Single Customer

      Revenues from Scotts Company, which acquired The Solaris Group in January
1999, accounted for 43%, 34%, and 54% of the Company's total revenues in 1999,
1998, and 1997, respectively. Revenues from Rhone-Poulenc AG Company accounted
for 10%, 14%, and 15% of the Company's total revenues in 1999, 1998, and 1997,
respectively. Revenues from American Cyanamid Company accounted for 11%, 16%,
and 14% of the Company's total revenues in 1999, 1998, and 1997, respectively.
Revenues from LinPac (previously Somerset Paper), the customer for which the
Company is providing fiber-recovery and water-clarification services, accounted
for 16% and 11% of revenues in 1999 and 1998.

      (viii)        Backlog

      The backlog of firm orders in the Company's Cellulose-based Products
segment was $799,000 as of January 1, 2000, and $419,000 as of January 2, 1999.
The Company believes that substantially all of the backlog at January 1, 2000,
will be shipped or completed during the next twelve months. Certain of these
orders may be canceled by the customer upon payment of a cancellation fee. In
addition, the Fiber-recovery and Water-clarification Services segment has a
ten-year contract to provide clean water and long fiber to a mill. The contract
may be canceled by either party within six months after the end of the fourth
year of the contract, or by the paper mill with one year's notice thereafter, if
certain benefits or profitability levels are not achieved. See Note 8 to
Consolidated Financial Statements in the Registrant's 1999 Annual Report to
Shareholders for other terms and conditions of the contract. The Company does
not believe that the size of its backlog is necessarily indicative of
intermediate or long-term trends in its business.



                                       5
<PAGE>

      (ix)          Government Contracts

      Not applicable.

      (x)           Competition

Fiber-recovery and Water-clarification Services

      The Company expects that its principal competitors for access to
papermaking byproducts will be landfills, which currently have a large market
share in both North America and Europe. The Company believes, however, that
landfill costs will tend to increase over time and that regulations governing
landfills will become more strict, particularly in Europe. The balance of the
papermaking byproducts produced in the U.S. and Europe is currently incinerated
or used to manufacture composting materials and other low-value industrial
products. The Company competes principally on its ability to offer long-term
environmentally acceptable byproducts management alternatives.

      Certain companies are seeking to develop technologies and services to
treat and process papermaking byproducts that are similar to those of the
Company. No assurance can be given that such technologies and services will not
be superior to those of the Company. As other companies attempt to provide
landfill services or byproducts processing capabilities, or both, to the pulp
and paper industry, the Company expects to encounter increasing competition.

      The Company believes that its approach to the management of environmental
problems associated with papermaking byproducts and its ability to take
advantage of Thermo Fibertek's name recognition, financial strength, and
experience constitute significant competitive advantages.

Cellulose-based Products

      The Company believes that the Company is currently the only producer of
paper-based agricultural carriers. GranTek's principal competitors in the U.S.
are producers of clay-based agricultural carriers for row crops and professional
turf protection, including Oil-Dri Corporation of America, Floridin/Engelhard,
Aimcor, and American Colloid, and producers of corncob-based granules
traditionally used in the home lawn and garden and professional turf markets,
including The Andersons, Mt. Pulaski, Green Products, Independence Cob, and
Junior Weisner. The Company's principal competitive advantages are that Biodac
is virtually dust-free and is more uniform in absorptivity and particle-size
distribution than are clay- and corncob-based granular carriers. Biodac is also
chemically neutral, requiring little or no chemical deactivation.

      NEXT Fiber Products will compete in the plastic lumber segment of the
building and construction industry, primarily with companies such as Trex
Company, Inc. and U.S. Plastic Lumber.

      As the Company attempts to develop new markets for the components of the
papermaking byproducts it processes, the Company will encounter competition from
established companies within those markets. Some of these competitors may have
substantially greater financial, marketing, and other resources than those of
the Company, and the Company expects that such competition may be intense. The
Company believes that in the absorbing-products industry price is a significant
competitive factor and therefore expects that the demand for the Company's
products in such markets will be significantly influenced by the Company's
prices for such products.

      (xii)         Environmental Protection Regulations

      The Company believes that compliance by the Company with federal, state,
and local environmental protection laws may materially affect the Company's
capital expenditures, earnings, and competitive position. Federal, state, and
local environmental laws govern air emissions and discharges into water, as well
as the generation, transportation, storage, treatment, and disposal of solid
waste. These laws establish standards governing most aspects of the


                                       6
<PAGE>

construction and operation of the Company's facilities. Additional information
required under this heading is included in the section labeled "Environmental
and Regulatory Risks" under "Forward-looking Statements" in the Registrant's
1999 Annual Report to Shareholders and is incorporated herein by reference.

      (xiii)        Number of Employees

      As of January 1, 2000, the Company employed 47 people. None of the
Company's employees is represented by a union. The Company believes that
relations with its employees are good.

(d)   Financial Information About Geographic Areas

      Not applicable.

(e)   Executive Officers of the Registrant
<TABLE>
<CAPTION>
<S>     <C>                        <C>   <C>
        Name                       Age   Present Title (Fiscal Year First Became Executive Officer)
        -------------------------  ---   ---------------------------------------------------------

        Dr. Yiannis A. Monovoukas  39    President and Chief Executive Officer (1996)
        Theo Melas-Kyriazi         40    Chief Financial Officer (1998)
        Paul F. Kelleher           57    Chief Accounting Officer (1996)

      Each executive officer serves until his successor is chosen or appointed by the Board of Directors
and qualified or until his earlier resignation, death, or removal.  Dr. Monovoukas has been President
and Chief Executive Officer of the Company since its incorporation in February 1996.  Dr. Monovoukas was
a Corporate Business Analyst at Thermo Electron from July 1995 through February 1996.  From 1993 through
June 1995, Dr. Monovoukas was a graduate student at the Harvard Business School.  From 1990 until 1993,
he was a staff scientist and engineer with Raychem Corporation, a materials science company, which he
joined upon completion of a Ph.D. program in chemical engineering at Stanford University.  Mr.
Melas-Kyriazi was appointed Chief Financial Officer of the Company and Thermo Electron on January 1,
1999.  He joined Thermo Electron in 1986 as Assistant Treasurer, and became Treasurer in 1988.  He was
named President and Chief Executive Officer of ThermoSpectra Corporation, a subsidiary of Thermo
Instrument Systems Inc., in 1994, a position he held until becoming Vice President of Corporate Strategy
for Thermo Electron in 1998.  Mr. Melas-Kyriazi remains a Vice President of Thermo Electron.  Mr.
Kelleher has held a comparable position for at least five years with Thermo Electron.  Mr. Melas-Kyriazi
and Mr. Kelleher are full-time employees of Thermo Electron, but devote such time to the affairs of the
Company as the Company's needs reasonably require.

Item 2.  Properties

      The Company believes that its facilities are in good condition and are
suitable and adequate for its present operations and that suitable space is
readily available if any leases are not extended. The location and general
character of the Company's principal properties by segment as of January 1,
2000, are:

Fiber-recovery and Water-clarification Services

      The Company leases a 6,000-square foot, stand-alone building in Bedford,
Massachusetts, which holds its administrative offices and research laboratory.
This lease expires in April 2001, subject to the Company's option to extend the
lease for two three-year terms. The Company leases the property on which its
fiber-recovery and water-clarification facility is located. The lease is for the
life of the related service contract.


                                       7
<PAGE>

Cellulose-based Products

      The Company owns approximately 3.3 acres of land in Green Bay, Wisconsin,
on which its 26,000-square foot processing plant is situated. In addition, the
Company leases a 21,000-square foot packaging plant under a lease that expires
in January 2001, a 30,000-square foot processing plant in Green Bay, Wisconsin,
under a lease that expires in December 2004, and a 14,000-square foot test
facility in Columbus, Indiana, under a lease that expires in December 2000.

Item 3.  Legal Proceedings

      Not applicable.

Item 4.  Submission of Matters to a Vote of Security Holders

      Not applicable.


                                  PART II

Item 5.  Market for Registrant's Common Equity and Related Stockholder Matters

(a)   Information concerning the market and market price for the Registrant's
      common equity securities and redemption rights and dividend policy is
      included under the sections labeled "Common Stock Market Information" and
      "Dividend Policy" in the Registrant's 1999 Annual Report to Shareholders
      and is incorporated herein by reference.

(b)   The Company sold 4,715,000 Units (each Unit consisting of one share of the Company's common stock
      and one redemption right which enables the holder to sell one share of the Company's common stock
      to the Company during the month of September 2000 or the month of September 2001 for $12.75 in
      cash), pursuant to a Registration Statement on Form S-1 (File No. 333-07585), which was declared
      effective by the Securities and Exchange Commission on September 13, 1996.  The managing
      underwriters of the offering were NatWest Securities Limited, Lehman Brothers, and Oppenheimer &
      Co., Inc.  The aggregate gross proceeds of the offering were $60,116,250.  The Company's total
      expenses in connection with the offering were $4,335,250, of which $3,913,450 was for underwriting
      discounts and commissions, $401,800 was for other expenses paid to persons other than directors or
      officers of the Company, persons owning more than 10% of any class of equity securities of the
      Company, or affiliates of the Company (collectively, Affiliates), and $20,000 was paid to Thermo
      Electron for certain corporate services rendered in connection with the offering.  The Company's
      net proceeds from the offering were $55,781,000.  As of January 1, 2000, the Company had expended
      $5,924,000 of such net proceeds for the purchase of property, plant, and equipment, including
      $3,573,000 for the construction of a water-clarification and fiber-recovery facility.  The Company
      has invested, from time to time, the balance of such net proceeds primarily in investment grade
      interest- or dividend-bearing instruments.  As of January 1, 2000, remaining net proceeds of
      $44,770,000 were invested directly with persons other than Affiliates and $5,087,000 were invested
      in an advance with Thermo Electron.

Item 6.  Selected Financial Data

      The information required under this item is included under the sections
labeled "Selected Financial Information" and "Dividend Policy" in the
Registrant's 1999 Annual Report to Shareholders and is incorporated herein by
reference.


                                       8
<PAGE>


Item 7.  Management's Discussion and Analysis of Financial Condition and Results
         of Operations

      The information required under this item is included under the heading
"Management's Discussion and Analysis of Financial Condition and Results of
Operations" in the Registrant's 1999 Annual Report to Shareholders and is
incorporated herein by reference.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

      The information required under this item is included under the caption
"Management's Discussion and Analysis of Financial Condition and Results of
Operations" in the Registrant's 1999 Annual Report to Shareholders and is
incorporated herein by reference.

Item 8.  Financial Statements and Supplementary Data

      The Registrant's Consolidated Financial Statements as of January 1, 2000,
and Supplementary Data are included in the Registrant's 1999 Annual Report to
Shareholders and are incorporated herein by reference.

Item 9.  Changes in and Disagreements with Accountants on Accounting and
         Financial Disclosure

      Not applicable.


                                    PART III

Item 10. Directors and Executive Officers of the Registrant

      The information concerning directors required under this item is
incorporated herein by reference from the material contained under the caption
"Election of Directors" in the Registrant's definitive proxy statement to be
filed with the Securities and Exchange Commission pursuant to Regulation 14A,
not later than 120 days after the close of the fiscal year. The information
concerning delinquent filers pursuant to Item 405 of Regulation S-K is
incorporated herein by reference from the material contained under the heading
"Section 16(a) Beneficial Ownership Reporting Compliance" under the caption
"Stock Ownership" in the Registrant's definitive proxy statement to be filed
with the Securities and Exchange Commission pursuant to Regulation 14A, not
later than 120 days after the close of the fiscal year.

Item 11. Executive Compensation

      The information required under this item is incorporated herein by
reference from the material contained under the caption "Executive Compensation"
in the Registrant's definitive proxy statement to be filed with the Securities
and Exchange Commission pursuant to Regulation 14A, not later than 120 days
after the close of the fiscal year.

Item 12. Security Ownership of Certain Beneficial Owners and Management

      The information required under this item is incorporated herein by
reference from the material contained under the caption "Stock Ownership" in the
Registrant's definitive proxy statement to be filed with the Securities and
Exchange Commission pursuant to Regulation 14A, not later than 120 days after
the close of the fiscal year.

Item 13. Certain Relationships and Related Transactions

      The information required under this item is incorporated herein by
reference from the material contained under the caption "Relationship with
Affiliates" in the Registrant's definitive proxy statement to be filed with the
Securities and Exchange Commission pursuant to Regulation 14A, not later than
120 days after the close of the fiscal year.


                                       9
<PAGE>

                                    PART IV

Item 14.  Exhibits, Financial Statement Schedules, and Reports on Form 8-K

(a,d)  Financial Statements and Schedules

       (1)The consolidated financial statements set forth in the list below are
          filed as part of this Report.

       (2)The consolidated financial statement schedule set forth in the list
          below is filed as part of this Report.

       (3)Exhibits filed herewith or incorporated herein by reference are set
          forth in Item 14(c) below.

       List of Financial Statements and Schedules Referenced in this Item 14

       Information incorporated by reference from Exhibit 13 filed herewith:

          Consolidated Statement of Income
          Consolidated Balance Sheet
          Consolidated Statement of Cash Flows
          Consolidated Statement of Comprehensive Income and Shareholders'
               Investment
          Notes to Consolidated Financial Statements
          Report of Independent Public Accountants

       Financial Statement Schedules filed herewith:

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

(b)    Reports on Form 8-K

       None.

(c)    Exhibits

       See Exhibit Index on the page immediately preceding exhibits.


                                       10
<PAGE>

                                  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.

Date:  March 21, 2000          THERMO FIBERGEN INC.


                               By: /s/ Yiannis A. Monovoukas
                                   Yiannis A. Monovoukas
                                   President, Chief Executive Officer, and
                                        Director

      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 indicated below, as of March 21, 2000.

Signature                               Title


By:  /s/ Dr. Yiannis A. Monovoukas      President, Chief Executive Officer, and
     Dr. Yiannis A. Monovoukas          Director


By:  /s/ Theo Melas-Kyriazi             Chief Financial Officer
     Theo Melas-Kyriazi


By:  /s/ Paul F. Kelleher               Chief Accounting Officer
     Paul F. Kelleher


By:  /s/ Anne T. Barrett                Director
     Anne T. Barrett


By:  /s/ Francis L. McKone              Director
     Francis L. McKone


By:  /s/ Jonathan W. Painter            Director
     Jonathan W. Painter


By:  /s/ William A. Rainville           Chairman of the Board and Director
     William A. Rainville


By:  /s/ Roger D. Wellington            Director
     Roger D. Wellington






                                       11
<PAGE>
                                 EXHIBIT INDEX
Exhibit
Number         Description of Exhibit

 3.1           Certificate of Incorporation of the Company, as amended (filed as Exhibit 3.1 to the
               Registrant's Registration Statement on Form S-1 [Reg. No. 333-07585] and incorporated
               herein by reference).

 3.2           By-Laws of the Company (filed as Exhibit 3.2 to the Registrant's Registration Statement
               on Form S-1 [Reg. No. 333-07585] and incorporated herein by reference).

 4.1           Form of Guarantee of Thermo Electron Corporation (filed as Exhibit 4.1 to the
               Registrant's Registration Statement on Form S-1 [Reg. No. 333-07585] and incorporated
               herein by reference).

 4.2           Guarantee Agreement among the Company, Thermo Electron, and the Representatives of the
               Underwriters (filed as Exhibit 4.2 to the Registrant's Registration Statement on Form S-1
               [Reg. No. 333-07585] and incorporated herein by reference).

 4.3           Form of Common Stock Certificate (filed as Exhibit 4.3 to the Registrant's Registration
               Statement on Form S-1 [Reg. No. 333-07585] and incorporated herein by reference).

 4.4           Form of Redemption Right Certificate (filed as Exhibit 4.4 to the Registrant's
               Registration Statement on Form S-1 [Reg. No. 333-07585] and incorporated herein by
               reference).

10.1           Asset Transfer Agreement dated as of July 2, 1996, between Thermo Fibertek Inc. and the
               Company (filed as Exhibit 10.1 to the Registrant's Registration Statement on Form S-1
               [Reg. No. 333-07585] and incorporated herein by reference).

10.2           License and Supply Agreement dated as of July 2, 1996, between Thermo Fibertek and the
               Company (filed as Exhibit 10.2 to the Registrant's Registration Statement on Form S-1
               [Reg. No. 333-07585] and incorporated herein by reference).

10.3           Corporate Services Agreement dated July 2, 1996, between Thermo
               Electron and the Company (filed as Exhibit 10.3 to the
               Registrant's Registration Statement on Form S-1 [Reg. No.
               333-07585] and incorporated herein by reference).

10.4           Thermo Electron Corporate Charter, as amended and restated effective
               January 3, 1993 (filed as Exhibit 10.1 to Thermo Electron's
               Annual Report on Form 10-K for the fiscal year ended January 2,
               1993 [File No. 1-8002] and incorporated herein by reference).

10.5           Tax Allocation Agreement dated as of July 2, 1996, between Thermo
               Fibertek and the Company (filed as Exhibit 10.5 to the
               Registrant's Registration Statement on Form S-1 [Reg. No.
               333-07585] and incorporated herein by reference).

10.6           Amended and Restated Master Guarantee Reimbursement and Loan
               Agreement dated as of December 8, 1997, between Thermo Fibertek
               and the Company (filed as Exhibit 10.8 to the Registrant's Annual
               Report on Form 10-K for the year ended January 3, 1998 [File No.
               1-12137] and incorporated herein by reference).

10.7           Lease dated as of April 12, 1996, by and between Al and Lee
               Realty and the Company (filed as Exhibit 10.9 to the Registrant's
               Registration Statement on Form S-1 [Reg. No.
               333-07585] and incorporated herein by reference).


                                       12
<PAGE>

Exhibit
Number         Description of Exhibit

10.8           Master Cash Management, Guarantee Reimbursement and Loan Agreement dated as of June 1,
               1999, between the Registrant and Thermo Electron (filed as Exhibit 10.1 to the
               Registrant's Quarterly Report on Form 10-Q for the quarter ended July 3, 1999 [File No.
               1-12137] and incorporated herein by reference).

10.9           Amended and Restated Equity Incentive Plan of the Registrant
               (filed as Exhibit 10.4 to the Registrant's Quarterly Report on
               Form 10-Q for the quarter ended July 3, 1999 [File No. 1-12137]
               and incorporated herein by reference).

               In addition to the stock-based compensation plans of the
               Registrant, the executive officers of the Registrant may be
               granted awards under stock-based compensation plans of Thermo
               Electron and Thermo Fibertek for services rendered to the
               Registrant or to such affiliated corporations. The terms of such
               plans are substantially the same as those of the Registrant's
               Equity Incentive Plan.

10.10          Amended and Restated Deferred Compensation Plan for Directors of the Registrant (filed as
               Exhibit 10.3 to the Registrant's Quarterly Report on Form 10-Q for the quarter ended July
               3, 1999 [File No. 1-12137] and incorporated herein by reference).

10.11          Amended and Restated Directors Stock Option Plan of the Registrant (filed as Exhibit 10.2
               to the Registrant's Quarterly Report on Form 10-Q for the quarter ended July 3, 1999
               [File No. 1-12137] and incorporated herein by reference).

10.12          Form of Indemnification Agreement for Officers and Directors of the Company (filed as
               Exhibit 10.14 to the Registrant's Registration Statement on Form S-1 [Reg. No. 333-07585]
               and incorporated herein by reference).

10.13          Restated Stock Holding Assistance Plan and Form of Promissory Note (filed as Exhibit
               10.14 to the Registrant's Annual Report on Form 10-K for the year ended January 3, 1998
               [File No. 1-12137] and incorporated herein by reference).

13             Annual Report to Shareholders for the year ended January 1, 2000
               (only those portions incorporated herein by reference).

21             Subsidiaries of the Registrant.

23             Consent of Arthur Andersen LLP.

27             Financial Data Schedule.
</TABLE>