<PAGE>

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 10-K

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

        For the fiscal year ended:                           Commission File No.
            JANUARY 31, 2000                                        1-4488

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

                                  MESABI TRUST
             (Exact name of registrant as specified in its charter)

            NEW YORK                                               13-6022277
    (State or other jurisdiction of                            (I.R.S. Employer
     incorporation or organization)                          Identification No.)

                           C/O BANKERS TRUST COMPANY
                        CORPORATE TRUST AND AGENCY GROUP
                                  P.O. BOX 318
                             CHURCH STREET STATION
                               NEW YORK, NEW YORK
                                   10008-0318
                    (Address of principal executive offices)

               Registrant's telephone number, including area code:
                                 (212) 250-6519

`      Securities registered pursuant to Section 12(b) of the Act:
              UNITS OF BENEFICIAL INTEREST IN MESABI TRUST
        Securities registered pursuant to Section 12(g) of the Act: NONE

           Indicate by check mark whether the Registrant (1) has filed all
reports required to be filed by Section 13 or 15(d) of the Securities Exchange
Act of 1934 during the preceding 12 months (or for such shorter period that the
Registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days. YES /X/ NO / /

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

         As of April 20, 2000, the aggregate market value of the Units of
Beneficial Interest held by non-affiliates of the registrant, based on the
closing price as reported on the New York Stock Exchange, aggregated
approximately $36,613,996*. As of April 20, 2000, 13,120,010 Units of Beneficial
Interest were outstanding.

-------------------------------
*        Includes approximately $42,469 representing the market value, as of
         April 20, 2000, of 15,100 Units the beneficial ownership of which is
         disclaimed by affiliates (see Item 12 herein).

<PAGE>

           Certain items in Parts I and II incorporate information by
reference from the Annual Report of the Trustees of Mesabi Trust to the
Holders of Certificates of Beneficial Interest for the fiscal year ended
January 31, 2000, which is annexed hereto and filed herewith as Exhibit 13.1.

                                     PART I

ITEM 1.    BUSINESS.

           (a)  GENERAL DEVELOPMENT OF BUSINESS.

           The information under the headings "Mesabi Trust," "The Trust
Estate," "Leasehold Royalties" and "Land Trust and Fee Royalties" set forth
on pages 7 through 11 of the Annual Report of the Trustees of Mesabi Trust
for the fiscal year ended January 31, 2000 (the "Annual Report") is
incorporated herein by reference. Certain capitalized terms used below in
this Part I are defined in the Annual Report.

           Mesabi Trust ("Mesabi Trust" or the "Trust"), formed pursuant to
an Agreement of Trust dated July 18, 1961 (the "Agreement of Trust"), is a
trust organized under the laws of the State of New York. Mesabi Trust holds
all of the interests formerly owned by Mesabi Iron Company, including all
right, title and interest in the Amended Assignment of Peters Lease, the
Amended Assignment of Cloquet Lease, the beneficial interest in the Mesabi
Land Trust and all other assets and property identified in the Agreement of
Trust. The Amended Assignment of Peters Lease relates to an Indenture made as
of April 30, 1915 among East Mesaba Iron Company, Dunka River Iron Company
and Claude W. Peters (the "Peters Lease") and the Amended Assignment of
Cloquet Lease relates to an Indenture made May 1, 1916 between Cloquet Lumber
Company and Claude W. Peters (the "Cloquet Lease").

           The Trust will terminate twenty-one (21) years after the death of
the survivor of twenty-five (25) persons named in an exhibit to the Agreement
of Trust. The youngest person on this exhibit is now 39 years old.

           (b)  FINANCIAL INFORMATION ABOUT INDUSTRY SEGMENTS.

           Substantially all of the Trust's revenue, operating profits and
assets relate to one business segment--iron ore mining.

           (c)  NARRATIVE DESCRIPTION OF BUSINESS.

           The Agreement of Trust specifically prohibits the Trustees from
entering into or engaging in any business. This prohibition applies even to
business activities the Trustees deem necessary or proper for the
conservation and protection of the Trust Estate. Accordingly, the Trustees'
activities in connection with the administration of Trust assets are limited
to collecting income, paying expenses and liabilities, distributing net
income and protecting and conserving the assets held.

           Pursuant to a ruling from the Internal Revenue Service, which
ruling was based on the terms of the Agreement of Trust including the
prohibition against entering into any business, the Trust is not taxable as a
corporation for Federal income tax purposes. Instead, the holders of the
Units of Beneficial Interest (the "Unitholders") are considered as "owners"
of the Trust and the Trust's income is taxable directly to the Unitholders.

           Leasehold royalty income constitutes the principal source of the
Trust's revenue. Royalty rates are determined in accordance with the terms of
Mesabi Trust's leases and assignments of leases. Until August 17, 1989, the
overriding royalty was based on the quantity and iron content of pellets
shipped by Reserve Mining Company ("Reserve") from Mesabi Trust lands,
although Mesabi Trust did not receive

                                       2

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any royalty income from May 1986 until July 1990 because Reserve filed a
Chapter 11 bankruptcy petition and suspended its operations. On August 17,
1989, Cyprus Northshore Mining Corporation ("Cyprus NMC") purchased
substantially all of Reserve's assets, including Reserve's interest in the
Mesabi Trust lands. At the same time, Mesabi Trust entered into certain
agreements with Reserve's Chapter 11 Trustee and Cyprus NMC (the "Amended
Assignment Agreements"). The Amended Assignment Agreements modified the
method of calculating overriding royalties payable to Mesabi Trust and
transferred Reserve's interest in the Mesabi Trust lands to Cyprus NMC.
Pursuant to the Amended Assignment Agreements, overriding royalties are
determined by both the volume and selling price of iron ore products shipped.
In 1994, Cyprus NMC was sold by its parent corporation to Cleveland-Cliffs
Inc. ("CCI") and renamed Northshore Mining Corporation ("Northshore"). CCI
now operates Northshore as a wholly-owned subsidiary.

           In its Annual Report for the year ended December 31, 1999 ("CCI's
Annual Report"), CCI, parent company of Northshore, the lessee/operator of
Mesabi Trust iron ore interests, stated that it was continuing to evaluate
whether to build a facility to produce pig iron at CCI's Northshore Mine in
Minnesota that would produce premium grade pig iron. CCI stated in the Report
that while progress has been made in a number of areas on the project, a
decision relative to proceeding with this project has been delayed by
uncertainty about market conditions and timing of state environmental
permitting. These statements were previously included in CCI's Annual Report
for the year ended December 31, 1998. Because of the preliminary nature of
this information, the Mesabi Trustees are unable to determine at this time
how the addition of a pig iron facility (if the project proceeds) would
impact overall revenues of Mesabi Trust. As indicated elsewhere in this
report, the Trust's revenues are currently derived almost entirely from iron
ore pellet production and sales.

           Mesabi Trust has no employees, but it engages independent
consultants to assist the Trustees in monitoring, among other things, the
amount and sales prices of minerals shipped by Northshore from Silver Bay,
Minnesota. As noted above, the information regarding amounts and sales prices
of shipped minerals is used to compute the royalties payable to Mesabi Trust
by Northshore. Bankers Trust Company, one of the Trustees, also performs
certain administrative functions for Mesabi Trust.

ITEM 2.    PROPERTIES.

           The information under the heading "The Trust Estate" set forth on
page 7 of the Annual Report of the Trustees of Mesabi Trust for the fiscal
year ended January 31, 2000 is incorporated herein by reference.

           The Peters Lease provides that each leasehold estate will continue
until the reserves of iron ore, taconite and other minerals or materials on
the land subject to the Peters Lease are exhausted. The Mesabi Lease
terminates when the Peters Lease terminates. The Cloquet Lease, executed in
1916, terminates in the year 2040. If Northshore decides to terminate or
surrender one or more of these leases, it must first give Mesabi Trust at
least six months' notice of its intention to do so and, at Mesabi Trust's
request, reassign all of such leases to Mesabi Trust. If any such
reassignment occurs, Northshore must transfer the lease interests to Mesabi
Trust free and clear of liens, except public highways. In return, Mesabi
Trust must assume Northshore's future obligations as lessee under the
reassigned leases.

           The Trustees have neither made nor caused to be made any surveys
or test drillings to ascertain the iron ore reserves on any land subject to
the Peters Lease or the Cloquet Lease. However, initial surveys and test
drillings made by Mesabi Iron Company many years ago indicated that these
lands contained accessible reserves of at least 1-1/2 billion tons of
mineable raw material, capable of yielding approximately 500 million tons of
concentrated product. In CCI's Annual Report, CCI estimated that there
currently remains enough ore reserve in the Peters and Cloquet Lease Lands to
produce

                                       3

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concentrated product for 81 years of mining at current extraction rates.
Little or no commercial ore deposits exist in the Mesabi Lease Lands.

ITEM 3.    LEGAL PROCEEDINGS.

           None.

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

           None.

                                     PART II

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

           The information set forth in the section titled "Certificates of
Beneficial Interest" on page 12 of the Annual Report of the Trustees of
Mesabi Trust for the fiscal year ended January 31, 2000 is incorporated
herein by reference.

ITEM 6.    SELECTED FINANCIAL DATA.

           The information set forth in the sections titled "Selected
Financial Data" and "Reserves and Distributions" on pages 2 and 12,
respectively, of the Annual Report of the Trustees of Mesabi Trust for the
fiscal year ended January 31, 2000 is incorporated herein by reference.

ITEM 7.    TRUSTEES' DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
           OF OPERATION.

           The information set forth in the sections titled "Trustees'
Discussion and Analysis of Financial Condition and Results of Operations,"
"Income and Expense" and "Reserves and Distributions" on pages 2-6, 11-12 and
12, respectively, of the Annual Report of the Trustees of Mesabi Trust for
the fiscal year ended January 31, 2000 is incorporated herein by reference.

ITEM 7A.   QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK.

           Not applicable.

ITEM 8.    FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA.

           The financial statements, including the independent auditor's
report thereon, filed as a part of this report, are presented on pages F-1
through F-10 and are incorporated herein by reference.

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

           None.

                                       4

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                                    PART III

ITEM 10.   DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT.

           There are no directors or executive officers of the registrant.
The Agreement of Trust provides for a Corporate Trustee and four Individual
Trustees (collectively, the "Trustees"). Generally, Trustees continue in
office until their resignation or removal. Any Trustee may be removed at any
time, with or without cause, by the holders of two-thirds in interest of the
Trust Certificates then outstanding. In the case of an Individual Trustee, a
successor is also appointed if the Individual Trustee dies, becomes incapable
of acting or is adjudged bankrupt or insolvent. In the case of the Corporate
Trustee, a successor is also appointed if a receiver of the Corporate Trustee
or of its property is appointed, or if any public officer takes charge or
control of the Corporate Trustee or of its property or affairs for the
purpose of rehabilitation, conservation or liquidation.

           The present Trustees of Mesabi Trust and their respective ages,
terms in office as Trustees, and business experience during the past five
years are set forth in the following table:

<TABLE>
<CAPTION>

                                                            Trustee                    Business Experience
             Name                       Age                  Since                    During Past Five Years
             ----                       ---                 -------                   ----------------------
<S>                                     <C>                 <C>              <C>
Bankers Trust Company                   N/A                   1961           Trust Company

David J. Hoffman                        64                    1977           Mining geologist; Until January 1988,
                                                                             President of Towne Mines Exploration
                                                                             Company, Inc., a privately-held mining
                                                                             corporation.

Richard G. Lareau                       71                    1990           Partner in the law firm of Oppenheimer
                                                                             Wolff & Donnelly LLP; Director of
                                                                             Ceridian Corporation, Nash Finch
                                                                             Company and Northern Technologies
                                                                             International Corporation.


Ira A. Marshall, Jr.                    77                    1976           Private investor and self-employed
                                                                             petroleum engineer; Until February
                                                                             1986, Director and Vice President
                                                                             of New American Fund, Inc.,  a
                                                                             closed-end investment trust.

Norman F. Sprague III                   52                    1981           Private investor; Orthopedic surgeon.
</TABLE>

ITEM 11.   TRUSTEES' COMPENSATION.

           The Agreement of Trust was amended October 25, 1982 (the
"Amendment"). Pursuant to the Amendment, each Individual Trustee receives at
least $20,000 in annual compensation for services as Trustee. Each year,
annual Trustee compensation is adjusted up or down (but not below $20,000) in
accordance with changes from the November 1981 level of 295.5 (the "1981
Escalation Level") in the All Commodities Producer Price Index (with 1967 =
100 as a base). The All Commodities Producer Price Index is published by the
U.S. Department of Labor. The adjustment is made at the end of each fiscal

                                       5

<PAGE>

year and is calculated on the basis of the proportion between (a) the level
of such index for the November preceding the end of such fiscal year and (b)
the 1981 Escalation Level.

           Also pursuant to the Amendment, Bankers Trust Company, as the
Corporate Trustee, receives annual compensation in an amount equal to the
greater of (i) $20,000, or such other amount determined in accordance with
the adjustments described in the preceding paragraph, or (ii) one quarter of
one percent (1/4 of 1%) of the Trust Moneys, exclusive of proceeds of sale of
any part of the Trust Estate (as such terms are defined in the Trust
Agreement), received by the Trustees and distributed to Trust Certificate
Holders.

           Additionally, each year the Corporate Trustee receives $62,500 (or
more, if unanimously approved by the Individual Trustees) to cover clerical
and administrative services to Mesabi Trust other than services customarily
performed by a registrar or transfer agent.

           The following table sets forth the cash compensation paid to the
Trustees through January 31, 2000, for services in all capacities as Trustees
to Mesabi Trust during the fiscal year ended January 31, 2000.

<TABLE>
<CAPTION>

                                   CASH COMPENSATION TABLE

           (A)                              (B)                           (C)
          Name                     Capacity in which served         Cash Compensation
          ----                     ------------------------         -----------------
<S>                                  <C>                              <C>
Bankers Trust Company                  Corporate Trustee                $88,100*

David J. Hoffman                       Individual Trustee               $25,600

Richard G. Lareau                      Individual Trustee               $25,600

Ira A. Marshall, Jr.                   Individual Trustee               $25,600

Norman F. Sprague III                  Individual Trustee               $25,600
</TABLE>

*  Does not include $19,958 of fees and disbursements paid to Bankers Trust
   Company as registrar and transfer agent of the Units.

ITEM 12.   SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND TRUSTEES.

           The following table sets forth information concerning each person
known to Mesabi Trust to own beneficially more than 5% of the Trust's Units
outstanding as of April 3, 2000. Such information has been obtained from
Mesabi Trust's records and a review of statements filed with Mesabi Trust
pursuant to Section 13(d)-102 of the Securities Exchange Act of 1934 through
April 3, 2000.

<TABLE>
<CAPTION>

            Name and Address                  Amount of Beneficial             Percent of
         of Beneficial Owner(s)                Ownership of Units                Class
         ----------------------               --------------------             ----------
<S>                                           <C>                              <C>
Appaloosa Management L.P.,
 a Delaware Limited Partnership
and
David A. Tepper
26 Main Street
Chatham, New Jersey 07928                        655,500(1)                       4.99%
</TABLE>

                                       6

<PAGE>

------------------------
         (1)      According to a Schedule 13G dated May 4, 1998, filed by such
                  persons, which indicates that each of such persons has sole
                  voting power and sole dispositive power with respect to such
                  units. Appaloosa Management L.P. is general partner of
                  Appaloosa Investment Limited Partnership I. The general
                  partner of Appaloosa Management L.P. is Appaloosa Partners,
                  Inc., of which David Tepper is the sole shareholder and
                  President. Appaloosa Management L.P. acts as an investment
                  advisor to Palomino Fund Ltd. ("PLF"). Of the 655,500 Units
                  reported, 327,750 are owned by Appaloosa Investment Limited
                  Partnership I and 327,750 are owned by PLF.

           The table below sets forth information as to the Units of Beneficial
Interest in Mesabi Trust beneficially owned as of March 15, 2000 by the Trustees
individually and as a group.

<TABLE>
<CAPTION>

                                       Amount of Beneficial            Percent of
       Name                             Ownership of Units                Class
       ----                            --------------------           ------------
<S>                                    <C>                            <C>
Bankers Trust Company(1)                        3,000                 Less than 1%

David J. Hoffman(2)                            38,100                 Less than 1%

Richard G. Lareau                              15,000                 Less than 1%

Ira A. Marshall, Jr.(3)                        51,000                 Less than 1%

Norman F. Sprague III                          12,700                 Less than 1%

All Trustees as a group                       116,800                 Less than 1%
</TABLE>
-------------------

(1)      In addition to the Units indicated above, Bankers Trust Company holds,
         on behalf of various customers, Units in its Fiduciary Department in
         so-called "directed" accounts. Bankers Trust Company has no voting or
         investment power over, and thus no beneficial interest in, such Units.

(2)      Includes 15,100 Units owned by Mr. Hoffman's wife, over which Mr.
         Hoffman does not have any investment or voting power and as to which
         Mr. Hoffman disclaims any beneficial ownership.

(3)      These Units consist of (a) 50,000 Units owned indirectly by Mr.
         Marshall through a family trust of which Mr. Marshall is the sole
         trustee and (b) 1,000 Units over which Mr. Marshall has joint voting
         and investment power.

ITEM 13.   CERTAIN RELATIONSHIP AND RELATED TRANSACTIONS.

           Mr. Richard G. Lareau, who became a Trustee on March 7, 1990, is a
senior partner in the law firm of Oppenheimer Wolff & Donnelly LLP, of
Minneapolis, Minnesota. That firm has been retained by Mesabi Trust since 1961
to act with respect to matters of Minnesota law, and was retained in 1991 by the
Trustees other than Mr. Lareau to act as general counsel.

                                       7

<PAGE>

                                     PART IV

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

     (a) 1.   FINANCIAL STATEMENTS:

          The following Financial Statements are incorporated in this reporting
          reference from the pages noted in our Annual Agreement of Trustees for
          the Year Ended January 31, 2000:

              Independent Auditor's Report - page F-1

              Balance Sheets as of January 31, 2000 and 1999 - page F-2

              Statements of Income for the years ended January 31, 2000, 1999
              and 1998 - page F-3

              Statements of Unallocated Reserve and Trust Corpus for the years
              ended January 31, 2000, 1999 and 1998 - page F-4

              Statements of Cash Flows for the years ended January 31, 2000,
              1999 and 1998 - page F-5

              Notes to Financial Statements - pages F-6 through F-10

          2.  FINANCIAL STATEMENT SCHEDULES:

          None required.

         Schedules other than those listed above have been omitted because they
are not applicable or the required information is included in the financial
statements or notes thereto.

          3.  EXHIBITS:

<TABLE>
<CAPTION>

     Item No.       Item                                       Filing Method
     --------       ----                                       -------------
     <S>            <C>                                        <C>
      3             Agreement of Trust dated as of July 18,    Incorporated by reference from Exhibit 3
                    1961..................................     to Mesabi Trust's Annual Report on Form
                                                               10-K for the fiscal year ended
                                                               January 31, 1987.


      3(a)          Amendment to the Agreement of Trust        Incorporated by reference from Exhibit
                    dated as of October 25, 1982               3(a) to Mesabi Trust's Annual Report on
                                                               Form 10-K for the fiscal year ended
                                                               January 31, 1988.
</TABLE>
                                       8

<PAGE>

<TABLE>
<CAPTION>

     Item No.       Item                                       Filing Method
     --------       ----                                       -------------
     <S>            <C>                                        <C>

      4             Instruments defining the rights of Trust   Incorporated by reference from Exhibit 4
                    Certificate Holders                        to Mesabi Trust's Annual Report on Form
                                                               10-K for the fiscal year ended
                                                               January 31, 1987.

      10(a)         Peters Lease..........................     Incorporated by reference from Exhibits 10(a)
                                                               - 10(d) to Mesabi Trust's Annual Report on
                                                               Form 10-K for the fiscal year ended January
                                                               31, 1987.


      10(b)         Amendment Assignment of Peters Lease..     Incorporated by reference from Exhibits 10(a)
                                                               - 10(d) to Mesabi Trust's Annual Report on
                                                               Form 10-K for the fiscal year ended January
                                                               31, 1987.

      10(c)         Cloquet Lease.........................     Incorporated by reference from Exhibits 10(a)
                                                               - 10(d) to Mesabi Trust's Annual Report on
                                                               Form 10-K for the fiscal year ended January
                                                               31, 1987.

      10(d)         Assignment of Cloquet Lease...........     Incorporated by reference from Exhibits 10(a)
                                                               - 10(d) to Mesabi Trust's Annual Report on
                                                               Form 10-K for the fiscal year ended January
                                                               31, 1987.


      10(e)         Modification of Lease and Consent to       Incorporated by reference from Exhibit
                    Assignment dated as of October 22, 1982    10(e) to Mesabi Trust's Annual Report on
                                                               Form 10-K for the fiscal year ended
                                                               January 31, 1988.


      10(f)         Amendment of Assignment, Assumption and    Incorporated by reference from Exhibit A
                    Further Assignment of Peters Lease....     to Mesabi Trust's Report on Form 8-K
                                                               dated August 17, 1989.


      10(g)         Amendment of Assignment, Assumption and    Incorporated by reference from Exhibit B
                    Further Assignments of Cloquet Lease..     to Mesabi Trust's Report on Form 8-K
                                                               dated August 17, 1989.

      13.1          Annual Report of the Trustees of Mesabi
                    Trust for the fiscal year ended January
                    31, 2000..............................     Filed herewith.

      27.1          Financial Data Schedule...............     Filed herewith.
</TABLE>

                                       9

<PAGE>

        (b)         REPORTS ON FORM 8-K FILED IN THE FOURTH
                    QUARTER:

                    None.

                                   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.

Dated:  April 4, 2000
                                               MESABI TRUST


                                               By:   Bankers Trust Company
                                                     Corporate Trustee

                                               By:    /s/ Daniel M. Chipko
                                                     -----------------------
                                                     Daniel M. Chipko
                                                     Associate


         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.

/s/ Daniel M. Chipko                                 April 4, 2000
--------------------------------------------
Daniel M. Chipko
Associate
Bankers Trust Company

/s/ David J. Hoffman                                 April 4, 2000
--------------------------------------------
David J. Hoffman
Individual Trustee

/s/ Richard G. Lareau                                April 4, 2000
--------------------------------------------
Richard G. Lareau
Individual Trustee

/s/ Ira A. Marshall, Jr.                             April 4, 2000
--------------------------------------------
Ira A. Marshall, Jr.
Individual Trustee

/s/ Norman F. Sprague III                            April 4, 2000
--------------------------------------------
Norman F. Sprague III
Individual Trustee

                                      10