Recently, therapeutic trial of unresectable hepatocellular carcinoma with radioiodinated fatty acid esters ison going study as one of the promising treatment modality. The purpose of study is to calculate the tumor as wellas the tumor edge doses by means of external count methods using 1-131-Lipiodol paraffin phatoms. Theradioactivity of each tumor phantoms ranging from 2-5cm in diameter were measured with TLD and lon chamber methods and compared to external count method of Gamma camera computer system. The tumor dosimetry in patients withintrahepatic 1-131-Lipiodol infusion can be calculated for those baseline studies of phantoms. Results as follows:1. The tumor doses calculated by Quimby equation were similar to TLD dose measurements of tumor paraffine phantoms. 2. The tumor edge dose will be delivered about 10% of total tumoral doses and decreased lower following inverse square law. 3. The radioactivity counts(CPM) of tumor phantoms related to the tumor diameter and depth canbe applied to dose calculations in the human subjects after consideration of transmission factor.