We treated synchronous hepatic metastases in colorectal cancers with combined modality therapy including hepatic resection, selective intra-arterial infusion chemotherapy, and thermocoagulation therapy using a microwave tissue coagulator and compared the value of such therapies. Synchronous hepatic metastases were noted in 563 patients with colorectal cancer who had undergone surgery in our department over the past ten years. Forty-four patients were studied. Six patients underwent hepatic resection only (group A). Another six were subjected to hepatic resection and the residual lesions were treated with selective intra-arterial infusions and thermocoagulation therapy (group B). Fourteen patients were treated with either selective or subselective intra-arterial infusions (group C). The remaining 18 patients were treated in other ways (group D). Cumulative survival, estimated by the Kaplan-Meier method, was compared. One- and three-year cumulative survival rates of patients were 100% and 74% in group A, 100% and 67% in group B, 62% and 0% in group C, and 38% and 5% in group D, respectively. H1 patients accounted for 83% in group A, 33% in group B, 7% in group C, and 22% in group D. The high rate of survival in group A was because of the greater number of H1 patients. One- and three-year survival rated among H2-H3 patients were 100% and 54% in group B, 62% and 0% in group C, and 35% and 14% in group D, respectively. Survival of H2-H3 patients was higher in group B than in group C or D.