One hundred twenty-two chemotherapy-naive patients with histologically confirmed colorectal adenocarcinoma were entered into a randomized trial comparing infusional fluorouracil (FU) versus cisplatin (CDDP) and FU. In both groups, patients received continuous infusion FU 1,000 mg/m2/d for 5 consecutive days every 4 weeks. Patients randomized to CDDP/FU also received CDDP 20 mg/m2 intravenous (IV) bolus on days 1 to 5 of each cycle. Patients were comparable in terms of age, performance status, baseline laboratory values, dominant sites of measurable disease, and percent of liver involvement. The partial response rate was significantly greater in patients who received CDDP/FU versus FU alone (25% v 3%, P = .001). Patients who received CDDP/FU experienced significantly greater toxicity compared with FU alone: grades 3 and 4 hematologic toxicity occurred in 22% and 0% of patients, respectively (P = .0001); grades 2 to 4 nausea and vomiting occurred in 80% and 15% of patients, respectively (P = .0001). There were no significant differences in either the duration of response (median, 6 and 4.7 months for CDDP/FU and FU groups, respectively) or survival (median 10, and 12 months, respectively). Compared with infusional FU alone, CDDP/FU provided a significantly greater partial response rate with increased toxicity, but it did not improve overall survival in patients with advanced colorectal carcinoma. Therefore, the use of CDDP/FU as routine therapy for the treatment of colorectal carcinoma cannot be recommended.