It has been shown that iodinated fatty acid esters such as Ethiodol(*) or Lipiodol(**) are selectively retained in hypervascular hepatic tumors following intrahepatic arterial admininstration. Such agents have been utilized in the detection and treatment of hepatocellular carcinoma (HCC) along with anticancer drug emulsions. Radioildination of Lipiodol(1-131-Lipiodol) was achieved by using a simple exchange method and the agent was used in the treatment of HCC following intrahepatic arterial-injection via superselective catheterization of tumor feeding vessels. Forty patients with HCC (massive 18; multinodular 12; infiltrative 10) were treated in an attempt to deliver a high dose of internal radiation; a cumulative tumor dose of 12,000 rad(120 GY) or higher was aimed in single or multiple procedures. Following therapy, the patients were divided into 2 groups, responsive or nonresponsive. Patients classfied as massive type responded to this treatment best (72.3%) followed by multinodular type (33.3%) and infiltrative type(10.0%). According to the size of tumor there was an 80.0% response for tumors of less than 5cm in diameter, 60.0%, between 5 to 8cm and 9.0% larger than 10cm in diameter. The clinical results of this treatment modality appear to be quite promising in the management of HCC, especially in the less than 8cm sized massive type of HCC. Also this method was able to not only provide long term local control but also a good quality of life without complications.