We have investigated the complications, toxicities, tumor response and survival rate with hepatic arterial (HA) chemotherapy for liver metastases from colorectal cancer. Forty-three patients with measurable liver metastases and 10 patients after the resection of liver metastases were treated with HA bolus mitomycin C (MMC) or continuous fluorouracil (5-FU) infusion between 1986 and 1994. The catheter- or reservoir-related complications such as catheter induced infection, subcutaneous reservoir pocket infection, or catheter or hepatic artery occlusion occurred in 14 patients (26%) mainly in our early cases. Severe gastritis or a gastroduodenal ulcer developed in 12 patients (23%), in particular after treatment with continuous infusion of 5-FU and when the catheter was placed into the gastroduodenal artery during laparotomy. An ulcer often caused a serious complication such as a duodeno-biliary fistula, penetration into the hepatic artery or duodenal perforation. Also noted were upper gastrointestinal symptoms in 26 patients, hepatic toxicities in 3 patients, and bone marrow depression in 4 patients. Because of these complications and toxicities, HA therapy was discontinued in more than 60% of the cases. The overall tumor response rate was 17%. However, in the cases which were treated by 5-FU continuous infusion for longer than 3 months, the response rate was higher than 60%. There was no significant difference in survival rate between HA therapy and systemic palliative chemotherapy. These results suggest that it is important to prevent gastrointestinal toxicities in order to allow continuation of HA continuous 5-FU infusion therapy which could provide a higher response rate and a better survival for colorectal cancer patients with liver metastases.