Fifty-one patients with metastatic colorectal carcinoma confined to the liver received intraarterial chemotherapy through the hepatic artery via a subcutaneous pump. The chemotherapy consisted of sequential 14-day infusions of floxuridine (FUDR) and dichloromethotrexate (DCMTX) or a 14-day infusion of FUDR and bolus mitomycin (MMC). Twenty-four patients (47%) developed hepatitis with an elevation of hepatic serum transaminase (serum glutamic oxaloacetic transaminase, SGOT, or serum glutamic-pyruvic transaminase, SGPT). The median time to develop hepatitis was 11 weeks after initiation of chemotherapy. The morphologic effects of chemotherapy were evaluated in eight patients with hepatitis. All the patients with hepatitis had normalization of the serum transaminases after temporary cessation of chemotherapy. There was a trend toward a greater chance of remission in patients who developed hepatitis. Sixty-seven percent of the patients with a therapeutic response had hepatitis, whereas only 33% of the patients without a response had hepatitis. However, this difference was not statistically significant. The occurrence of hepatitis was not related to FUDR dose, drug program (FUDR-DCMTX vs. FUDR-MMC), pump flow rate, hepatic arterial anatomy, sex, or age of the patients.