A vaccine consisting of recombinant vaccinia virus encoding the tumor-associated antigen carcinoembryonic antigen (CEA) and a TRIad of COstimulatory Molecules (B7-1, ICAM-1, and LFA-3; also called TRICOM). Vaccination with recombinant vaccinia-CEA(6D)-TRICOM vaccine stimulates the host immune system to mount a T-cell response against tumor cells expressing the CEA antigen. The use of TRICOM in the vaccine may elicit a greater antitumor cytotoxic T lymphocyte (CTL) immune response compared to the use of vaccinia-CEA alone.