Fifty-five patients with metastatic colorectal carcinoma confined to the liver were treated with hepatic arterial infusion of floxuridine and mitomycin C. Tumour response rate was 43.4% and median overall survival was 11 months. Prolonged survival was associated with intentional or inadvertent occlusion of the hepatic artery. The median survival of twenty-four patients with arterial occlusion (15 months) was significantly higher than that of thirty-one patients without arterial occlusion (8 months).