DSM, an agent which occludes arterial blood flow temporarily, was experimentally proved to enhance the uptake of co-administered anti-cancer drugs in the target organ and, conversely, to reduce the systemic side effects. Intra-arterial chemotherapy combined with MMC and DSM was performed on eight cases of unresectable metastatic liver carcinoma. The primary site of all these cases (7 gastric, 1 rectal) was resected. A catheter was inserted into the proper hepatic artery via the gastroduodenal artery, and the other end was connected to an implantable drug delivery system which was placed at the abdominal wall. DSM (180 to 900 mg) mixed with MMC (4 to 20 mg) was injected through the system every one, two or three weeks. The response rate in evaluable 7 cases was 57% (4 partial response, 1 minor response, 2 no change) and prognoses in the frequently treated group (7 times or more) were better than in the group with less frequent treatment (3 times or less). Pain (25.0%), nausea and vomiting (20.6%), and high fever (11.8%) were side effects, but they could be treated by medication. Our results suggest that intra-arterial chemotherapy combined with MMC and DSM is one of the effective treatments for unresectable metastatic liver carcinoma.