In our previous randomized trial of advanced gastric cancer patients, the addition of epirubicin (EPI) to 5-fluorouracil (FU) with folinic acid (FA) resulted in an improved response rate and survival in the responder patients. Preclinical studies also showed an enhancement of FU and anthracyclines with interferon. To evaluate the possibility of human lymphoblastoid interferon (IFN) to enhance the therapeutic activity of the FA-FU + EPI combination regimen, 39 advanced gastric cancer patients received: FU at 375 mg/m2 i.v. immediately after FA (l-isomer form) at 100 mg/m2 i.v. for 5 consecutive days; EPI at 60 mg/m2 i.v. on day 1, and IFN 3 MU s.c. for 7 consecutive days, starting 2 days before the FA-FU administration. Thirty-seven patients were evaluable for response and toxicity. Twelve partial responses were observed with an overall response rate of 32% (95% CI, 17-48%). The median response duration was 6 months, and the median survival time was 8 months. Toxicity was mild and no grade 4 side effects or treatment-related deaths were observed. However, the addition of IFN to the FA-FU + EPI regimen did not improve response, duration of response or survival.