A clinical trial of 5-day Cisplatin combined with loading course 5-fluorouracil (5-FU) was conducted in 37 patients with advanced colorectal carcinoma. Objective tumor responses were seen in 10 of 34 patients (29%) who had not received prior chemotherapy. The estimated median survival for previously untreated patients is 26 weeks measured from the onset of therapy. Toxicity consisted primarily of leukopenia, vomiting, and reversible renal insufficiency. This combination of cisplatin and intensive course 5-FU has demonstrated Phase II activity in patients with advanced colorectal cancer. A controlled trial is now in progress to prospectively compare this regimen with full dose single agent 5-FU.