A 59-year-old man was admitted to our hospital for advanced sigmoid colon carcinoma with synchronous multiple liver metastases. The patient received sigmoidectomy with regional lymph node dissection on June 8, 1998. We started intra-arterial combination chemotherapy on July 1, 1998. MMC (4 mg/body) was administered via rapid intra-arterial infusion on day 1. After MMC administration, 5-day intra-arterial continuous infusion of 5-FU at 500 mg/body/day was performed with oral administration of LV (30 mg/body/day). The treatment cycle was defined as every three weeks. The patient was treated with 4 courses of chemotherapy. From September 30, he received intra-arterial infusion of bolus MMC 4 mg/body, LV 6 mg/body and 5-FU 1,000 mg/body/4 hrs every two weeks with oral administration of Tegafur-uracil 400 mg/day. After 4 intra-arterial chemotherapy sessions, the metastatic liver tumors disappeared except for a focus in the right lobe. Therefore we decided to give the remnant liver metastasis percutaneous microwave coagulation therapy (PMCT). He obtained a complete remission in the liver metastases after two PMCT (70 W, 60 sec) sessions. Intra-arterial chemotherapy is effective for unresectable metastatic liver tumors from colon cancer. If a patient shows a partial response on the metastatic tumors through the chemotherapy, one must consider other modalities such as PMCT.