We report a patient with synchronous multiple liver metastases from rectal cancer associated with ulcerative colitis. Because the liver tumors were unresectable, we performed total proctocolectomy and hepatic intra-arterial cisplatin infusion with systemic oral administration of fluorouracil. A complete response was obtained. The patient is alive without sign of recurrence 5 years postoperatively. Hepatic intra-arterial administration of cisplatin should be considered in the treatment of unresectable liver metastases from colorectal cancer.