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                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                             ---------------------
                                  FORM 10-K/A
                               (Amendment No. 1)
(Mark One)
 
       [X]       ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                               SECURITIES EXCHANGE ACT OF 1934
 
                  FOR THE FISCAL YEAR ENDED DECEMBER 31, 1998
 
                                       OR
 
        [ ]     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 1-9864
 
                         EL PASO TENNESSEE PIPELINE CO.
             (Exact name of registrant as specified in its charter)
 
<TABLE>
<S>                                                 <C>
                     DELAWARE                                           76-0233548
         (State or other jurisdiction of                             (I.R.S. Employer
          incorporation or organization)                           Identification No.)
 
             EL PASO ENERGY BUILDING
              1001 LOUISIANA STREET
                  HOUSTON, TEXAS                                          77002
     (Address of principal executive offices)                           (Zip Code)
</TABLE>
 
       REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE: (713) 420-2131
 
          SECURITIES REGISTERED PURSUANT TO SECTION 12(B) OF THE ACT:
 
<TABLE>
<CAPTION>
                                                                NAME OF EACH EXCHANGE
                    TITLE OF EACH CLASS                          ON WHICH REGISTERED
                    -------------------                         ---------------------
<S>                                                            <C>
8 1/4% Cumulative Preferred Stock, Series A.................   New York Stock Exchange
</TABLE>
 
        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]
 
     STATE THE AGGREGATE MARKET VALUE OF THE VOTING STOCK HELD BY NON-AFFILIATES
OF THE REGISTRANT. Aggregate market value shall be computed by reference to the
price at which the stock was sold, or the average bid and asked prices of such
stock, as of the specified date within 60 days prior to the date of filing.
 
<TABLE>
<CAPTION>
                                                                  MARKET VALUE
         CLASS OF VOTING STOCK AND NUMBER OF SHARES                   HELD
          HELD BY NON-AFFILIATES AT MARCH 16, 1998              BY NON-AFFILIATES
          ----------------------------------------              -----------------
<S>                                                             <C>
8 1/4% Cumulative Preferred Stock, Series A, 6,000,000
  shares                                                          $328,125,000*
</TABLE>
 
---------------
 
*  Based upon the closing price on the Composite Tape for the 8 1/4% Cumulative
   Preferred Stock, Series A, on March 16, 1999.
 
     INDICATE THE NUMBER OF SHARES OUTSTANDING OF EACH OF THE REGISTRANT'S
CLASSES OF COMMON STOCK, AS OF THE LATEST PRACTICABLE DATE.
 
     Common Stock, par value $.01 per share. Shares outstanding on March 16,
1999: 1,971
 
                      DOCUMENTS INCORPORATED BY REFERENCE
 
     List hereunder the following documents if incorporated by reference and the
part of the Form 10-K (e.g., Part I, Part II, etc.) into which the document is
incorporated: El Paso Tennessee Pipeline Co.'s definitive Proxy Statement for
the 1999 Annual Meeting of Stockholders, to be filed not later than 120 days
after the end of the fiscal year covered by this report, is incorporated by
reference into Part III.
 
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<PAGE>   2
 
                         EL PASO TENNESSEE PIPELINE CO.
                                EXPLANATORY NOTE
 
     El Paso Tennessee Pipeline Co. hereby amends its Annual Report on Form 10-K
for the year ended December 31, 1998, to include for the following periods
Restated Financial Data Schedules as a result of a tax-free internal
reorganization effected by the parent company, El Paso Energy Corporation:
 
Year Ended December 31, 1997
Year Ended December 31, 1996
Quarter Ended March 31, 1998
Quarter Ended June 30, 1998
Quarter Ended September 30, 1998
Quarter Ended March 31, 1997
Quarter Ended June 30, 1997
Quarter Ended September 30, 1997
 
     Accordingly, the undersigned hereby amends the Exhibit Index of its Annual
Report on Form 10-K for the year ended December 31, 1998, by inserting in the
Exhibit Index Exhibits 27(2) through 27(9) filed herewith. All exhibits other
than Exhibits 27(2) through 27(9) that are marked with an asterisk(*) in the
Exhibit List were filed with the registrant's Form 10-K on March 18, 1999.
<PAGE>   3
 
                                   SIGNATURES
 
     Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this amendment to be signed on its behalf by the
undersigned, thereunto duly authorized.
 
<TABLE>
<S>                                            <C>
                                               EL PASO TENNESSEE PIPELINE CO.
 
Date: April 5, 1999                                        /s/ JEFFREY I. BEASON
                                               ----------------------------------------------
                                                             Jeffrey I. Beason
                                                       Vice President and Controller
                                                         (Chief Accounting Officer)
</TABLE>
<PAGE>   4
 
                         EL PASO TENNESSEE PIPELINE CO.
 
                                  EXHIBIT LIST
                               DECEMBER 31, 1998
 
     Exhibits not incorporated by reference to a prior filing are designated by
an asterisk; all exhibits not so designated are incorporated herein by reference
to a prior filing as indicated.
 
   
<TABLE>
<CAPTION>
        EXHIBIT
         NUMBER                                  DESCRIPTION
        -------                                  -----------
<C>                      <S>
           2.A           -- Amended and Restated Merger Agreement dated as of June
                            19, 1996, among EPNG, El Paso Merger Company and EPTPC
                            (Exhibit 2.A to EPNG's Registration Statement on Form S-4
                            filed August 27, 1996, File No. 333-10911).
           2.B           -- Distribution Agreement, dated as of November 1, 1996,
                            among EPTPC, New Tenneco Inc. and Newport News
                            Shipbuilding Inc. (Exhibit 2.2 to EPNG's Form 8-K filed
                            December 26, 1996, File No. 1-2700); Amendment No. 1 to
                            Distribution Agreement entered into as of December 11,
                            1996, by and among EPTPC, New Tenneco Inc. and Newport
                            News Shipbuilding Inc. (Exhibit 2.3 to EPNG's Form 8-K/A
                            filed January 21, 1997, File No. 1-2700).
           3.A           -- Certificate of Incorporation as amended and supplemented
                            as of March 1, 1995 (Exhibit 3(a)(1) to EPTPC Form 10-K
                            for 1994, File No. 1-9864); Certificate of Retirement of
                            Preferred Stock Redeemed or Purchased, dated February 16,
                            1996; Certificate of Elimination of the Series A
                            Cumulative Preferred Stock of Tenneco Inc. dated February
                            27, 1996; Certificate of Elimination of the Variable Rate
                            Preferred Stock of Tenneco Inc. dated February 27, 1996;
                            Certificate of Elimination of the Participating Preferred
                            Stock of Tenneco Inc. dated February 27, 1996;
                            Certificate of Designation, Preferences and Rights of
                            8 1/4% Cumulative Junior Preferred Stock, Series A, dated
                            November 18, 1996; Certificate of Amendment of
                            Certificate of Incorporation, dated December 11, 1996;
                            Certificate of Merger dated December 11, 1996; and
                            Certificate of Designation, Preferences and Rights of
                            8 1/2% Cumulative Junior Preferred Stock, Series B, dated
                            March 5, 1997 (Exhibit 3.A to EPTPC's Form 10-K for 1996,
                            File No. 1-9864); Certificate of Designation, Preferences
                            and Rights of 6 1/4% Cumulative Junior Preferred Stock,
                            Series C, dated March 4, 1998 (Exhibit 3.A.1 to EPTPC's
                            Form 10-K for 1997, File No. 1-9864).
          *3.A.1         -- Certificate of Elimination of 8 1/2% Cumulative Junior
                            Preferred Stock, Series B, dated January 14, 1999,
                            Certificate of Elimination of 6 1/4% Cumulative Junior
                            Preferred Stock, Series C, dated January 14, 1999.
           3.B           -- By-laws of EPTPC, as amended March 1, 1998 (Exhibit 3.B
                            to EPTPC's Form 10-K for 1997, File No. 1-9864).
           4.A           -- Indenture dated as of March 4, 1997, between TGP and The
                            Chase Manhattan Bank (Exhibit 4.1 to EPTPC's Form 10-K
                            for 1997, File No. 1-9864); First Supplemental Indenture
                            dated as of March 13, 1997, between TGP and The Chase
                            Manhattan Bank (Exhibit 4.2 to EPTPC's Form 10-K for
                            1997, File No. 1-9864); Second Supplemental Indenture
                            dated as of March 13, 1997, between TGP and The Chase
                            Manhattan Bank (Exhibit 4.3 to EPTPC's Form 10-K for
                            1997, File No. 1-9864); Third Supplemental Indenture
                            dated as of March 13, 1997, between TGP and The Chase
                            Manhattan Bank (Exhibit 4.4 to EPTPC's Form 10-K for
                            1997, File No. 1-9864); Fourth Supplemental Indenture
                            dated as of October 9, 1998, between TGP and The Chase
                            Manhattan Bank (Exhibit 4.2 to TGP's Form 8-K filed
                            October 9, 1998, File No. 1-4101).
         *18             -- Letter Regarding Change in Accounting Principles.
         *21             -- List of Subsidiaries.
      *27(1)             -- Financial Data Schedule for the Year Ended December 31,
                            1998.
      *27(2)             -- Financial Data Schedule for the Year Ended December 31,
                            1997.
      *27(3)             -- Financial Data Schedule for the Year Ended December 31,
                            1996.
      *27(4)             -- Financial Data Schedule for the Quarter Ended March 31,
                            1998.
      *27(5)             -- Financial Data Schedule for the Quarter Ended June 30,
                            1998.
      *27(6)             -- Financial Data Schedule for the Quarter Ended September
                            30, 1998.
      *27(7)             -- Financial Data Schedule for the Quarter Ended March 31,
                            1997.
      *27(8)             -- Financial Data Schedule for the Quarter Ended June 30,
                            1997.
      *27(9)             -- Financial Data Schedule for the Quarter Ended September
                            30, 1997.
</TABLE>
    
<PAGE>   5
 
UNDERTAKING
 
     The undersigned Registrant hereby undertakes, pursuant to Regulation S-K,
Item 601(b), paragraph (4)(iii), to furnish to the Securities and Exchange
Commission upon request all constituent instruments defining the rights of
holders of long-term debt of Registrant and its consolidated subsidiaries not
filed herewith for the reason that the total amount of securities authorized
under any of such instruments does not exceed 10 percent of the total
consolidated assets of Registrant and its consolidated subsidiaries.