An iodized oil such as Ethiodol or Lipiodol was selectively retained in the tumor vessels of the large hepatomas as well as in the small daughter hepatomas for long periods following the intra-arterial hepatic injection of such contrast material. The specific aim of the study is to deliver a high internal radiation dose to hepatocellular car- cinoma (HCC) in an attempt to control the disease. We were able to replace a sma11 fraction of the stable iodine (I-127) of the 37% iodine in Lipioclol by the I ' with 100% exehange efficiency. I ' labeled Lipiodol was injected through the super- selerted tumor feeding artery under superselection or into the proper hepatic arterial level of patients who have malignant hepatomas confirmed by aspiration cytology, serum AFP and various imaging modalities, Clinica! traial was performed on 43 cases during recent 6 months and follow-up observa- tion was carried out. No severe complications or other adverse reactions were encountered until nowdays. I"'"-Lipiodol was stable in vivo and no significant activity was noted in the ".hyroid, stomach, blood and urine after the injection. Only small fraction of radioisotope activity was noticed in the both side of lungs. Tumor to normal liver radio was very high. Therefore, 1 '-Lipiodol (or P-32-Lipiodol) will be effective delivering high internal radiation dose to the tumor while delivering small radiation doses to normal tisaues. Labeling, tumor dose caiculation and preliminary findings will be presented.