From January 1987 to December 1989, we performed a prospective study of transcatheter arterial chemoembolization therapy with iodized oil (Lipiodol) mixed with an anticancer agent. A new oil-soluble modification of FUdR, FUdR-C8 ester, was developed and dissolved in Lipiodol as an embolic material, which was administered to 36 patients with hepatomas. Water-soluble adriamycin emulsified in Lipiodol was used as control in 67 patients with hepatomas. Initial effects on tumors were observed as decrease of tumor size in 25.0% for the FUdR group and 17.9% for the control group. Alpha-fetoprotein decreased more than half in 41.9% of the FUdR group, and 16.1% of the ADM group. Six-month and one-year survivals were 74.2% and 46.8% for the FUdR group (median survival 317 days), whereas the control group yielded 61.0% and 28.3% survivals, respectively (median survival 191 days).