A patient with advanced intrahepatic cholangiocarcinoma had a tumor embolus in the right main branch of the portal vein and lymph node metastases. Hepatic arterial infusion (HAI) therapy with 5-FU (1 g/day) was given as a continuous infusion for 6 days. The treatment was repeated after a one-week interval. As a result the tumor diameter decreased by half, and the tumor embolus contracted. Cytoreductive surgery was then performed. The patient has been disease-free for over 9 months postoperatively with adjuvant HAI with 5-FU. We consider preoperative HAI with 5-FU (two courses of 1 g/day x 6 days) is both safe and effective.