Purpose: To assess the efficacy and tolerability of three treatments for patients with documented adenocarcinoma of the colon and/or rectum who have undergone complete resection of primary tumor and have nonresectable liver metastases that do not exceed 75% of the liver volume. Patients and Methods: A total of 168 patients at 25 treatment centers were enrolled onto this prospective, multicenter, randomized study, The three treatment arms were as follows: (1) fluorouracil (5-FU)/leucovorin (LV) administered via hepatic arterial infusion (HAI), (2) 5-FU/LV administered via intravenous (IV) infusion, and (3) fluorodeoxyuridine (FUDR) administered via HAI. Results: Median times to disease progression for the three treatment arms were as follows: 9.2 months for patients treated with HAI 5-FU/LV, 6.6 months for IV 5-FU/LV, and 5.9 months for HAI FUDR. Median survival times for patients treated with HAI 5-FU/LV, IV 5-FU/LV, and HAI FUDR were 18.7 months, 17.6 months, and 12.7 months, respectively. There was a nearly two-fold increase in time to progression in addition to a survival benefit among patients with an intrahepatic tumor burden of less than 25% who were treated with HAI 5-FU/LV. The most common adverse events were stomatitis, nausea and vomiting, skin irritation, diarrhea, and elevated serum levels of liver enzymes. Some patients exhibited severe reactions, including biliary sclerosis and chemical hepatitis. Conclusion: Although the use of HAI 5-FU/LV as a means of treating liver metastases after resection of colorectal carcinoma warrants further investigation, it cannot be recommended as a routine therapeutic measure at this time. (C) 2000 by American Society of Clinical Oncology.