50 patients with advanced gastrointestinal malignancies were treated with 5-fluorouracil (5FU), 1-(2-chloroethyl)3-(4-methylcyclohexyl)-1-nitrosourea (MeCCNU) and mitomycin C (Mito C). 43 patients, ...with diagnoses of colorectal, pancreatic or gastric cancer, were evaluable. 13 patients (30%) achieved complete remissions, and 4 achieved partial remissions. The median durations of responses in colorectal, pancreatic and gastric disease were 11.0, 11.0, and 11.5 months, respectively. Survival was definitely prolonged in responding patients with pancreatic and gastric carcinomas. The combination was well tolerated. Mucositis, leukopenia, and thrombocytopenia were the major toxicities that occurred. The quality of life was improved in all responding patients.