From May 1984 through December 1986, 141 patients with metastatic adenocarcinoma of the colon or rectum were entered on this Hoosier Oncology Group (HOG) trial evaluating the role of cisplatin in systemic therapy. Patients were stratified by the presence or absence of hepatic metastases and by performance status, and were subsequently randomized to receive fluorouracil (5-FU) (15 mg/kg/wk) alone or the same dose of 5-FU plus cisplatin (60 mg/m2 every 3 weeks). The total duration of treatment was six cycles (18 weeks). In 132 fully evaluable patients the objective response rates were 19% for 5-FU and 22% for 5-FU plus cisplatin. Statistically, the median survival times of 40 and 39 weeks were not significantly different (P = .62). However, the median duration of remission (MDR) was superior (P = .05) for 5-FU alone. This study fails to confirm clinically significant synergy of 5-FU plus cisplatin in the treatment of metastatic colorectal cancer.