Two studies were carried out to determine the activity and evaluate the toxicity of oral chemotherapy with uracil and tegafur in a 4:1 molar ratio (UFT) plus or minus calcium folinate in elderly patients with advanced colorectal cancer. In one study, 106 patients received a fixed dose of UFT 400 mg/day in two daily doses every 12 hours continuously, plus calcium folinate 45 mg/day administered in three divided doses every 8 hours continuously. In study 2, calcium folinate was omitted, and the dose of UFT was increased to 400 mg/m2/day in two daily doses administered every 12 hours continuously to 95 patients. Treatments for both studies were administered until grade 3 or grade 4 toxicity occurred or disease progressed. The response rate among the 96 available patients in study 1 was 17.7% (95% confidence interval [CI], 10% to 27%); 41 patients (43%) achieved an objective response or stable disease. Overall survival was 13.7 months with a statistically significant difference between patients with no progressive disease and patients with progressive disease (P < .01). In study 2, 62 of 95 patients have now been evaluated for response. The response rate was 21% (95% CI, 13% to 30%); 38 patients (61%) experienced an objective response or stable disease. The overall survival for study 2 has not yet been evaluated. Toxicity was generally mild, consisting of grade 3 nausea/vomiting (6% in study 1 and 2% in study 2), grade 3 or grade 4 diarrhea (11% in study 1 and 7% in study 2), plus one case of grade 3 mucositis in study 1. These findings suggest that chemotherapy with UFT (with or without modulation with calcium folinate) is feasible for elderly patients with advanced colorectal carcinoma.