<PAGE>

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

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549





                                    FORM 8-K

                                 CURRENT REPORT

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




        Date of report (date of earliest event reported): August 1, 2003




                         MARTIN MIDSTREAM PARTNERS L.P.
             (Exact name of Registrant as specified in its charter)



<Table>
<S>                                  <C>                               <C>
        DELAWARE                            000-50056                             05-0527861
(State of incorporation              (Commission file number)          (I.R.S. employer identification number)
    or organization)


            4200 STONE ROAD
             KILGORE, TEXAS                                                          75662
(Address of principal executive offices)                                           (Zip code)
</Table>




       Registrant's telephone number, including area code: (903) 983-6200


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




<PAGE>



ITEM 7. FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS.

         (c) EXHIBITS

         Pursuant to the rules and regulations of the Securities and Exchange
Commission, the attached exhibit is deemed to have been furnished pursuant to

Item 9 and should not be deemed to be "filed" under the Securities Exchange Act
of 1934.


<Table>
<Caption>
        EXHIBIT
        NUMBER           DESCRIPTION
        -------          -----------
<S>                      <C>
         99.1            --    Press release dated August 1, 2003.
</Table>



ITEM 9. REGULATION FD DISCLOSURE.

         On August 1, 2003, Martin Midstream Partners L.P. (the "Partnership")
issued a press release announcing that it plans to issue its results for the
second quarter ended June 30, 2003, on Friday, August 8, 2003, after the market
closes. The Partnership also announced that a teleconference to review the
second quarter results will be held on Monday, August 11, 2003, at 4:00 p.m.
Central Time. A copy of the press release is included as an exhibit to this
Current Report. Pursuant to the rules and regulations of the Securities and
Exchange Commission, such exhibit and the information set forth therein and
herein is deemed to have been furnished and shall not be deemed to be "filed"
under the Securities Exchange Act of 1934.


                                       2


<PAGE>



                                   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 hereunto duly authorized.

                                        MARTIN MIDSTREAM PARTNERS L.P.

                                        By:  Martin Midstream GP LLC
                                        Its: General Partner


Date:  August 1, 2003                       By: /s/ ROBERT D. BONDURANT
                                               --------------------------------
                                                Robert D. Bondurant,
                                                Executive Vice President and
                                                Chief Financial Officer

                                       3

<PAGE>



                                INDEX TO EXHIBITS


<Table>
<Caption>
EXHIBIT
NUMBER              DESCRIPTION
-------             -----------
<S>                 <C>
99.1                --    Press release dated August 1, 2003.
</Table>




                                       4




<PAGE>
                         MARTIN MIDSTREAM PARTNERS L.P.
                      TO ISSUE SECOND QUARTER 2003 RESULTS
                            AND HOLD CONFERENCE CALL

         KILGORE, Texas, August 1, 2003 /PRNewswire-FirstCall via COMTEX/ --
Martin Midstream Partners L.P. (Nasdaq: MMLP) today said that it plans to
publicly announce its second quarter 2003 results after the market closes on
Friday, August 8, 2003.

         A conference call to review the second quarter 2003 results will be
held on Monday, August 11, 2003, at 4:00 p.m. Central Time. The conference call
can be accessed by calling (877) 407-9205. An audio replay of the conference
call will be available by calling (877) 660-6853 from 10:00 a.m. Central Time on
August 12, 2003 through 10:59 p.m. Central Time on August 19, 2003. The access
codes for the conference call and the audio replay are as follows: Account No.
1628; Conference ID No. 72890. The audio replay of the conference call will also
be archived on the Internet at http://www.martinmidstream.com.

         During the conference call, management will discuss certain
non-generally accepted accounting principle financial measures for which
reconciliations to the most directly comparable GAAP financial measures will be
provided in MMLP's announcement concerning its second quarter 2003 results and
available
 on the investor relations page of the Company's website.

About Martin Midstream Partners

         Martin Midstream Partners provides marine transportation, terminalling,
distribution and midstream logistical services for producers and suppliers of
hydrocarbon products and by-products, specialty chemicals and other liquids. The
Company also manufactures and markets sulfur-based fertilizers and related
products and owns an unconsolidated non-controlling 49.5% limited partnership
interest in CF Martin Sulphur L.P., which operates a sulfur storage and
transportation business. MMLP operates primarily in the Gulf Coast region of the
United States.

         Additional information concerning the Company is available via the
worldwide web at http://www.martinmidstream.com.

Forward-Looking Statements

         Statements about Martin Midstream Partners' outlook and all other
statements in this release other than historical facts are forward-looking
statements within the meaning of the Private Securities Litigation Reform Act of
1995. These forward-looking statements and all references to financial estimates
rely on a number of assumptions concerning future events and are subject to a
number of uncertainties and other factors, many of which are outside its
control, that could cause actual results to differ materially from such
statements. While MMLP believes that the assumptions concerning future 



<PAGE>

events are reasonable, it cautions that there are inherent difficulties in
anticipating or predicting certain important factors. These factors include, but
are not limited to: adverse weather conditions; reliance on its unconsolidated
non-controlling interest in CF Martin Sulphur L.P.; the incurrence of material
liabilities that are not fully covered by insurance; the price volatility and
the supply availability of hydrocarbon products and by-products; restrictions in
its debt agreements; the prospects for future acquisitions and its ability to
make future acquisitions; the performance of acquired businesses; the
seasonality of its business; the competition in the industry; changes in
regulations on the federal, state and local level that are applicable to its
business; the cost of attracting and retaining highly skilled personnel; the
loss of significant commercial relationships with Martin Resource Management
Corporation ("MRMC"); interruption in operations at its facilities; federal
regulations applicable to its marine vessels and regulations effecting the
domestic tank vessel industry; cost reimbursements it is required to pay to
MRMC; conflicts of interest and competition with MRMC; the decisions made by and
the control of its general partner; and a decision by the IRS to treat MMLP as a
corporation. A discussion of these factors, including risks and uncertainties,
is set forth from time to time in the Company's filings with the Securities and
Exchange Commission. Martin Midstream Partners disclaims any intention or
obligation to revise any forward-looking statements, including financial
estimates, whether as a result of new information, future event, or otherwise.

Contacts:

Robert D. Bondurant, Executive Vice President and Chief Financial Officer of
Martin Midstream GP LLC, the Company's general partner.