The single and combined antitumor effects of adriamycin and a major histocompatibility complex non-restricted human cytotoxic T cell line (TALL-104) were evaluated in severe combined immunodeficient (SCID) mice engrafted subcutaneously with a biopsy sample from a patient with a highly metastatic gastric carcinoma. Chemotherapy was initiated 3 weeks after tumor implantation, when local growth was advanced, and consisted of 2 weekly injections of adriamycin. gamma-irradiated (40 Gy) TALL-104 cells were administered daily for 2 weeks, starting 1 day after the end of chemotherapy. While TALL-104 cells or adriamycin alone did not inhibit tumor growth, synergistic antitumor effects were seen with the two treatments combined. These findings suggest that chemotherapy in conjunction with cell therapy are effective in overcoming tumor resistance to single therapeutic agents through mechanisms independent from the host immune system.