The case of a 59 year-old man with sigmoid colon cancer and synchronous liver metastases is described in this report. Sigmoid colectomy and partial hepatectomy were performed, and hepatic arterial cannulation was done for prevention of hepatic recurrence. Heparin was injected to prevent catheter-related clots, and no anticancer drugs were used. He did well without signs of recurrence for 5 years after the initial operation. After we stopped the heparin administration, recurrence was detected in the liver. The patient underwent repeat hepatectomy, and he is now doing well without recurrence 2 years after the second operation. The clinical course of this case suggests that heparin may prevent liver metastasis of colorectal cancer.