6-K

QuickLinks -- Click here to rapidly navigate through this document

FORM 6-K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16 of

the Securities Exchange Act of 1934

For the month of:        February 11, 2004

TRICOM, S.A.
(Translation of registrant's name into English)

Avenida Lope de Vega No. 95, Santo Domingo, Dominican Republic
(Address of principal executives offices)

        Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

        Form 20-F    X     Form 40-F          

        Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

        Yes         No    X    

        If "Yes" is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): 82-            

        The press release on February 11, 2004, a copy of each is attached as Exhibit 99.1, is incorporated by reference into this Form 6-K.

        Exhibits.

        The following exhibits are filed with this report:

        99.1 — Press Release, dated February 11, 2004, of TRICOM, S.A.

        [Signature on following page.]

2

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.

		TRICOM, S.A
Dated: February 11, 2004	By:	/s/  CARL H. CARLSON Carl H. Carlson Chief Executive Officer

3

QuickLinks

FORM 6-K SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Report of Foreign Private Issuer Pursuant to Rule 13a-16 or 15d-16 of the Securities Exchange Act of 1934
TRICOM, S.A. (Translation of registrant's name into English)
Avenida Lope de Vega No. 95, Santo Domingo, Dominican Republic (Address of principal executives offices)
SIGNATURES

EX-99.1

QuickLinks -- Click here to rapidly navigate through this document

EXHIBIT 99.1

Tricom Announces Board Changes

        SANTO DOMINGO, Dominican Republic, Feb. 11—Tricom, S.A. (NYSE: TDR) today announced that Ricardo Valdez Albizu, 45, has joined the Company's board of directors.

        Mr. Valdez Albizu is chairman and chief executive officer of a leading diversified industrial park in the Dominican Republic. Mr. Valdez Albizu has extensive experience working with the Dominican private sector having held a number of executive and senior management positions for the main interest groups representing exporters, industries as well as free zone companies in the Dominican Republic. Mr. Valdez Albizu is a former commodities futures trader at Merrill Lynch, and served as agent representative for Paine Webber, Savannah Foods and Industries, among others. Mr. Valdez Albizu graduated from Universidad Autonoma de Santo Domingo where he received his law degree in 1984.

        The Company also announced that Marcos Troncoso has resigned from the Company's board of directors. Mr. Troncoso will remain as Secretary of the Board of Directors and will continue to advise and represent the Company in legal, regulatory and other corporate matters.

About TRICOM

        Tricom, S.A. is a full service communications services provider in the Dominican Republic. We offer local, long distance, mobile, cable television and broadband data transmission and Internet services. Through Tricom USA, we are one of the few Latin American based long distance carriers that is licensed by the U.S. Federal Communications Commission to own and operate switching facilities in the United States. Through our subsidiary, TCN Dominicana, S.A., we are the largest cable television operator in the Dominican Republic based on our number of subscribers and homes passed. We also offer digital mobile integrated services including two-way radio and paging services in Panama using iDEN® technology. For more information about Tricom, please visit www.tricom.net

        For additional information, please visit Tricom's Investor Relations website at http://www.tdr-investor.com or contact our Investor Relations department at the above numbers.

QuickLinks

Tricom Announces Board Changes