<PAGE>   1
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM 10-Q

                  QUARTERLY REPORT UNDER SECTION 13 OR 15(d) OF
                       THE SECURITIES EXCHANGE ACT OF 1934



FOR THE QUARTER ENDED SEPTEMBER 30, 1998  COMMISSION FILE NUMBER 2-22997



                              MILLS MUSIC TRUST
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)



          NEW YORK                                              13-6183792
(STATE OR OTHER JURISDICTION OF                              (I.R.S. EMPLOYER
INCORPORATION OR ORGANIZATION)                              IDENTIFICATION NO.)



C/O MARINE MIDLAND BANK,   140 BROADWAY,   NEW YORK, NY           10015
               (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)         (ZIP CODE)



REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE (212) 658-6014




               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


NUMBER OF TRUST UNITS OUTSTANDING AS OF MARCH 10, 1998    277,712

<PAGE>   2
                          PART I - FINANCIAL STATEMENTS

Item 1.  Financial Information

                                MILLS MUSIC TRUST
                  STATEMENTS OF CASH RECEIPTS AND DISBURSEMENTS
         THREE MONTHS AND NINE MONTHS ENDED SEPTEMBER 30, 1998 AND 1997

                                   (UNAUDITED)





<TABLE>
<CAPTION>
                                      Three Months Ended                Nine Months Ended
                                          September 30                      September 30
                                          ------------                      ------------
                                     1998             1997             1998             1997
                                   ---------        ---------        ---------        ---------

Receipts:
<S>                                <C>              <C>              <C>              <C>      
      Mills Music, Inc.            $ 278,631        $ 326,735        $ 751,562        $ 813,904

Undistributed cash
      at beginning of
      the period                          11               13                8               20

Disbursements -
administrative expenses               (3,433)          (6,273)         (23,304)         (31,337)
                                   ---------        ---------        ---------        ---------

Balance available
      for distribution               275,209          320,475          728,266          782,587

Cash distribution
      to unit holders                275,185          319,786          728,242          781,898
                                   ---------        ---------        ---------        ---------

Undistributed cash at
      end of the period            $      24        $     689        $      24        $     689
                                   =========        =========        =========        =========

Cash distribution per
      unit (based on 277,712
        units outstanding)         $     .99        $    1.15        $    2.62        $    2.82
                                   =========        =========        =========        =========
</TABLE>


See accompanying Notes to Statements of Cash Receipts and Disbursements.
<PAGE>   3
                                                                          Page 3


                                MILLS MUSIC TRUST
             NOTES TO STATEMENTS OF CASH RECEIPTS AND DISBURSEMENTS
         THREE MONTHS AND NINE MONTHS ENDED SEPTEMBER 30, 1998 AND 1997

                                   (UNAUDITED)

NOTE 1.  ACCOUNTING POLICIES AND GENERAL INFORMATION

                     Mills Music Trust ("the Trust") was created in 1964 for the
               purpose of acquiring the rights to receive payments of a deferred
               contingent purchase price contract obligation payable by Mills
               Music, Inc. ("Mills"). The contingent payments are determined
               quarterly, and are based on a formula which takes into account
               gross royalty income from certain music copyrights and licenses
               of Mills, less royalties paid and amounts deducted by Mills in
               accordance with contract terms.

                     Payments from Mills to the Trust are made in March, June,
               September, and December, and include net royalty income of the
               preceding calendar quarter. The payments received are accounted
               for on a cash basis, as are expenses paid. The Declaration of
               Trust requires the distribution of all funds received by the
               Trust to the Unit holders after payment of expenses.

                     The statements of cash receipts and disbursements reflect
               only cash transactions and do not present transactions that would
               be included in financial statements presented on the accrual
               basis of accounting, as contemplated by generally accepted
               accounting principles.

                     There is no book value per unit because cumulative
               distributions are in excess of the initial investment in the
               Trust.

NOTE 2.  RELATED PARTY TRANSACTIONS

                     The Declaration of Trust provides that each trustee shall
               receive reimbursement for expenses reasonably incurred in the
               performance of his duties and annual compensation of $2,500 per
               year for his services as trustee, provided that such aggregate
               compensation to the trustees as a group may not exceed 3% of the
               monies received by the Trust in any year. The Declaration of
               Trust further provides for reimbursement to the corporate trustee
               for its clerical and administrative services to the Trust.
               Accordingly, Marine Midland Bank receives reimbursement for such
               services and for services performed as Registrar and Transfer
               Agent. The Declaration of Trust further provides that if any
               trustee performs unusual or extraordinary services, reasonable
               compensation for such services shall be paid, subject to certain



<PAGE>   4
                                                                          Page 4



                                MILLS MUSIC TRUST
             NOTES TO STATEMENTS OF CASH RECEIPTS AND DISBURSEMENTS
         THREE MONTHS AND NINE MONTHS ENDED SEPTEMBER 30, 1998 AND 1997
                                   (CONTINUED)

                                   (UNAUDITED)

               limitations and to prior confirmation by a majority in interest
               of Trust Certificate holders. Pursuant to these provisions,
               disbursements to related parties were made as follows for the
               nine months ended September 30, 1998 and 1997.

<TABLE>
<CAPTION>
                                           1998         1997
                                          ------       ------
     Trustee Fees:
<S>                                       <C>          <C>   
       Bernard D. Fischman                $1,875       $1,875
       Marine Midland Bank                 1,875        1,250

     Marine Midland Bank - Transfer
       Agent and Registrar                     0        5,932
</TABLE>

NOTE 3.  ROYALTY EXAMINATION

                     The Trust's claim against Belwin Mills Publishing
               Corporation, the former administrators of the Old Mills
               Catalogue, in connection with a 1987 royalty examination is
               pending final resolution by the Trust. It cannot be determined at
               this time, what, if any, amount may ultimately be received by the
               Trust.

                     No examination of royalty information has been performed
               subsequent to February, 1987.


NOTE 4.  FEDERAL INCOME TAXES

                     No provision for income taxes has been made since the
               liability is that of the unit holders and not the Trust.
<PAGE>   5
                                                                          Page 5


                          PART I - FINANCIAL STATEMENTS


Item 2.  Management's Discussion and Analysis of Results of Operations

                  The Trust's receipts from Mills Music, Inc. are derived from
         copyrights established prior to 1964 and such receipts fluctuate based
         upon public interest in the "nostalgia" appeal of older songs.



                           PART II - OTHER INFORMATION

               Items 1 through 6, inclusive, are not applicable.




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                                                                          Page 6



                                   SIGNATURES


               Pursuant to the requirements 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.


                                                    MILLS MUSIC TRUST
                                                      (Registrant)





Date October 12, 1998                       By:     BERNARD D. FISCHMAN
                                                Bernard D. Fischman,Trustee




Date October 12, 1998                       By:      MARCIA MARKOWSKI
                                                Marine Midland Bank
                                                Corporate Trustee