<PAGE>

                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                   FORM 10-K/A

                                 AMENDMENT NO. 3

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

For the fiscal year ended.......................................June 30, 2003


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

For the transition period from                   to
                               -----------------     -----------------


Commission File Number    0-5896
                        --------------------------------------------------------


                             JACO ELECTRONICS, INC.
                             ----------------------
             (Exact name of registrant as specified in its charter)

            New York                                      11-1978958
            --------                                      ----------
(State or other jurisdiction of             (I.R.S. Employer Identification No.)
incorporation or organization)

  145 Oser Avenue, Hauppauge, New York                       11788
  ------------------------------------                       -----
(Address of principal executive offices)                   (Zip Code)

Registrant's telephone number, including area code:               (631) 273-5500
                                                                  --------------

Securities registered pursuant to Section 12(b) of the Act: None

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

                          Common Stock, $0.10 per share
                          -----------------------------
                                (Title of Class)

      Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days.

                 Yes: X                                 No:
                     ---                                   ---

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

      Indicate by check mark whether the registrant is an accelerated filer (as
defined in Exchange Act Rule 12b-2).

                 Yes:                                   No: X
                     ---                                   ---

      The aggregate market value of voting common equity held by non-affiliates
of the registrant, computed by reference to the closing price on December 31,
2002 was $12,592,390. The registrant has no non-voting common equity.

      Number of shares outstanding of each class of Common Stock, as of
September 22, 2003: 5,927,082 shares (excluding 659,900 treasury shares).

                      DOCUMENTS INCORPORATED BY REFERENCE:

None.
<PAGE>
                                EXPLANATORY NOTE

This Amendment No. 3 on Form 10-K/A to our Annual Report on Form 10-K for the
year ended June 30, 2003, filed on September 29, 2003, as amended by our
Amendment No. 1 on Form 10-K/A thereto, filed on October 28, 2003, and our
Amendment No. 2 on Form 10-K/A thereto ("Amendment No. 2"), filed on March 31,
2004 (the "Form 10-K"), is being filed to amend the Form 10-K solely to file as
Exhibits 31.1 and 32.2 to Amendment No. 2 the Rule 13a-14(a)/15d-14(a)
Certifications of our Principal Executive Officer and our Principal Financial
Officer. Other than the foregoing, none of the information contained in the Form
10-K has been revised or amended.

ITEM 9A. CONTROLS AND PROCEDURES

An evaluation was performed, under the supervision and with the participation of
the Company's management, including the Company's Principal Executive Officer
and Principal Financial Officer, of the effectiveness of the design and
operation of the Company's disclosure controls and procedures (as defined in
Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934) as of
June 30, 2003. Based upon that evaluation, the Company's management, including
its Principal Executive Officer and Principal Financial Officer, has concluded
that the Company's disclosure controls and procedures are effective to ensure
that information required to be disclosed in the reports that the Company files
or submits under the Securities Exchange Act of 1934 is recorded, processed,
summarized and reported within the time periods specified in the Securities and
Exchange Commission's rules and forms. There have been no changes in the
Company's internal control over financial reporting or in other factors
identified in connection with this evaluation that occurred during the fiscal
year ended June 30, 2003 that have materially affected, or are reasonably likely
to materially affect, the Company's internal control over financial reporting.

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: April 23, 2004
                                        JACO ELECTRONICS, INC.


                                        By: /s/ Joel H. Girsky
                                            ------------------------------------
                                            Joel H. Girsky, Chairman, President
                                                and Treasurer (Principal
                                                Executive Officer)

                                        By: /s/ Jeffrey D. Gash
                                            ------------------------------------
                                            Jeffrey D. Gash, Executive Vice
                                                President - Finance and
                                                Secretary (Principal Financial
                                                and Accounting Officer)


                                       2