We experienced 5 cases of liver metastases from colorectal cancer, in which hepatic resection was carried out after down sizing by hepatic arterial infusion chemotherapy. In addition, a histological study about the effect of chemotherapy on the liver tumor was performed. Primary lesions were located at the sigmoid colon (2), cecum (1), descending colon (1) and rectum (1). We carried out hepatic arterial infusion chemotherapy using mainly 5-FU. The total amount of 5-FU was 10-81 g. Tumor volumes were reduced by 12.5-24%, and they were judged PR. However, surgery was indicated due to obstruction of the proper hepatic artery or other side effects. Postoperative courses were uneventful and the hospital stays were from 17-61 days, and all patients were still alive in tumor-free condition at writing. By the histological study of the excised specimen, we recognized not only remarkable fibrous changes or calcifications but also overt viable cancerous cells. We conclude that the option of hepatic resection after controlling the development of the cancer by hepatic arterial infusion chemotherapy is a rational strategy of treatment for liver metastasis from colorectal cancer.