In our institution, patients with multiple unresectable liver metastases from colorectal cancer have received 24-h continuous arterial infusion therapy of 5-fluorouracil (5-FU) 250 mg/body/day every 2 weeks for the past 11 years. Although the 5-year survival rate of those who underwent surgical resection was 35%, that of unresectable patients who received 5-FU arterial infusion was 24% at 2 years, 9% at 3 years, and 50% survived a median of 391 days. Furthermore, we were able to perform surgical resection of metastatic residual lesions in patients who responded to 5-FU arterial infusion. This therapy has proven so effective that the 3-year survival rate of these patients is now 38%, and complete cures are being achieved.