<PAGE>


                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                   FORM 10-KSB/A
                                (AMENDMENT NO. 1)

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

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


    For the fiscal year ended:               Commission file number:
    DECEMBER 28, 2002                        0-11201

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


                            MERRIMAC INDUSTRIES, INC.
             (Exact name of Registrant as specified in its charter)

    DELAWARE                                22-1642321
    (State of Incorporation)                (I.R.S. Employer Identification No.)

               41 FAIRFIELD PLACE, WEST CALDWELL, NEW JERSEY 07006
                    (Address of Principal Executive Offices)

                         REGISTRANT'S TELEPHONE NUMBER:
                                 (973) 575-1300

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

           SECURITIES REGISTERED PURSUANT TO SECTION 12(b) OF THE ACT:
                     COMMON STOCK, PAR VALUE $.01 PER SHARE

           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]

Indicate by check mark whether the Registrant is an accelerated filer (as
defined in Exchange Act Rule 12b-2). Yes [] No [X]

As of May 12, 2003, 3,120,591 shares of Common Stock of the Registrant were
outstanding. As of May 12, 2003, the aggregate market value of the Common Stock
of the Registrant (based upon the last reported sale price of the Common Stock
at that date by The American Stock Exchange), excluding shares owned
beneficially by affiliates, was approximately $5,724,499.

<PAGE>

DOCUMENTS INCORPORATED BY REFERENCE   N/A


                            MERRIMAC INDUSTRIES, INC.
                                   FORM 10-KSB/A
                         AMENDMENT NO. 1 TO FORM 10-KSB/A
                   FOR THE FISCAL YEAR ENDED DECEMBER 28, 2002

The Company's Form 10-KSB/A for the fiscal year ended December 28, 2002 is being
amended solely for the purpose of amending the Exhibit 99.1 to include the
certifications required pursuant to Section 906 of the Sarbanes-Oxley Act of
2002.

SIGNATURES

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

                             Merrimac Industries, Inc.


Date:  May 9, 2003           By: /s/ Mason N. Carter
--------------------------------------------------------------------------------
                                 Chairman, President and Chief Executive Officer



Date:  May 9, 2003           By: /s/ Robert V. Condon
--------------------------------------------------------------------------------
                                 Chief Financial Officer


CERTIFICATION
I, Mason N. Carter, certify that:

     1.   I have reviewed this Amendment No. 1 to the annual report on
          Form 10-KSB/A of Merrimac Industries, Inc.;

     2.   Based on my knowledge, this amendment to the annual report does not
          contain any untrue statement of a material fact or omit to state a
          material fact necessary to make the statements made, in light of the
          circumstances under which such statements were made, not misleading
          with respect to the period covered by this amendment to the annual
          report;

     3.   Based on my knowledge, the financial statements, and other financial
          information included in the annual report, fairly present in all
          material respects the financial condition, results of operations and
          cash flows of the registrant as of, and for, the periods presented in
          the annual report;

     4.   The registrant's other certifying officers and I are responsible for
          establishing and maintaining disclosure controls and procedures (as
          defined in Exchange Act Rules 13a-14 and 15d-14) for the registrant
          and we have:

          a)   Designed such disclosure controls and procedures to ensure that
               material information relating to the registrant, including its
               consolidated subsidiaries, is made known to us by others within
               those entities, particularly during the period in which this
               amendment to the annual report is being prepared;

          b)   Evaluated the effectiveness of the registrant's disclosure
               controls and procedures as of a date within 90 days prior to the
               filing date of this amendment to the annual report (the
               "Evaluation Date"); and

          c)   Presented in the annual report our conclusions about the
               effectiveness of the


<PAGE>

               disclosure controls and procedures based on our evaluation as of
               the Evaluation Date;

     5.   The registrant's other certifying officers and I have disclosed, based
          on our most recent evaluation, to the registrant's auditors and the
          audit committee of registrant's board of directors (or persons
          performing the equivalent function):


          a)   All significant deficiencies in the design or operation of
               internal controls which could adversely affect the registrant's
               ability to record, process, summarize and report financial data
               and have identified for the registrant's auditors any material
               weaknesses in internal controls; and

          b)   Any fraud, whether or not material, that involves management or
               other employees who have a significant role in the registrant's
               internal controls; and

     6.   The registrant's other certifying officers and I have indicated in the
          annual report whether or not there were significant changes in
          internal controls or in other factors that could significantly affect
          internal controls subsequent to the date of our most recent
          evaluation, including any corrective actions with regard to
          significant deficiencies and material weaknesses.



DATE: May 9, 2003
By: /s/ Mason N. Carter
    -------------------
NAME: Mason N. Carter
TITLE: Chairman, President and Chief Executive Officer



<PAGE>



CERTIFICATION
I, Robert V. Condon, certify that:
     1.   I have reviewed this Amendment No. 1 to the annual report on
          Form 10-KSB/A of Merrimac Industries, Inc.;

     2.   Based on my knowledge, this amendment to the annual report does not
          contain any untrue statement of a material fact or omit to state a
          material fact necessary to make the statements made, in light of the
          circumstances under which such statements were made, not misleading
          with respect to the period covered by this amendment to the annual
          report;

     3.   Based on my knowledge, the financial statements, and other financial
          information included in the annual report, fairly present in all
          material respects the financial condition, results of operations and
          cash flows of the registrant as of, and for, the periods presented in
          the annual report;

     4.   The registrant's other certifying officers and I are responsible for
          establishing and maintaining disclosure controls and procedures (as
          defined in Exchange Act Rules 13a-14 and 15d-14) for the registrant
          and we have:

          a)   Designed such disclosure controls and procedures to ensure that
               material information relating to the registrant, including its
               consolidated subsidiaries, is made known to us by others within
               those entities, particularly during the period in which this
               amendment to the annual report is being prepared;

          b)   Evaluated the effectiveness of the registrant's disclosure
               controls and procedures as of a date within 90 days prior to the
               filing date of this amendment to the annual report (the
               "Evaluation Date"); and

          c)   Presented in the annual report our conclusions about the
               effectiveness of the disclosure controls and procedures based
               on our evaluation as of the Evaluation Date;

     5.   The registrant's other certifying officers and I have disclosed, based
          on our most recent evaluation, to the registrant's auditors and the
          audit committee of registrant's board of directors (or persons
          performing the equivalent function):

<PAGE>

          a)   All significant deficiencies in the design or operation of
               internal controls which could adversely affect the registrant's
               ability to record, process, summarize and report financial data
               and have identified for the registrant's auditors any material
               weaknesses in internal controls; and

          b)   Any fraud, whether or not material, that involves management or
               other employees who have a significant role in the registrant's
               internal controls; and

     6.   The registrant's other certifying officers and I have indicated in the
          annual report whether or not there were significant changes in
          internal controls or in other factors that could significantly affect
          internal controls subsequent to the date of our most recent
          evaluation, including any corrective actions with regard to
          significant deficiencies and material weaknesses.


DATE: May 9, 2003
BY: /s/ Robert V. Condon
    --------------------
NAME: Robert V. Condon
TITLE: Chief Financial Officer