Fifteen patients (median age 62, with a mean Karnofsky performance status of 70%) presenting with advanced colorectal carcinoma were included in the study. The treatment combination consisted of 5-fluorouracil (800 mg/m2 in a 30 min infusion, days 1 and 8), teniposide (80 mg/m2 in i.v. push, day 1), and mitomycin-C (10 mg/m2 in i.v. push, day 1); therapy was resumed every 29 days. A partial objective response (for 4 months) was noted in one patient who had received no prior chemotherapy; the overall median survival of the 15 patients was 5 months. Toxicity was acceptable, with leukopenia (1 case), mucositis (1 case) and diarrhea (1 case), leading to drug dose reduction. Chemotherapy was stopped once owing to severe hematologic toxicity. With the doses and schedule used, the drug combination appears to have minimal activity in advanced colorectal cancer.