We examed intrahepatic and serum titer of Intracellular Adhesion Molecule-1 (ICAM-1) in Hepatocellular carcinoma (HCC) were determined, and investigated the relationship between serum titer of ICAM-1 (sICAM-1) and therapeutic effects and intrahepatic findings.[Materiale and Method] sICAM-1 were determined in 63 patients with HCC who were positive for serum HCV antibody. The course after TAE treatment was compared with changes in sICAM-1 titers. sICAM-1 titers were determined with EIA kits. Intrahepatic ICAM-1 were determined in unfixed frozen speciemens at light and electron microscopy by immunoperoxidase method using monoclonal antibody.[Result] Intrahepatic ICAM-1 were observed in cancer cell membrane. In EM, positive reaction products were existed on the endplasmic reticulum in cytoplasm and cell membrane in cancer cells. Intrahep atic ICAM-1 levels tended to be higher in poorly differenciated carcinoma (CA), but to be lower in the non cancerous area. The mean sICAM-1 titer was significantly higher in HCC group than in CAH and LC group. sICAM-1 titers were so depressed in many patients after TAE therapy that the relationship of sICAM-1 titers to the course of TAE therapy could not be studied to the full.[Conclusion] 1) Intrahepatic ICAM-1 were localized in endplasmic reticulum and cell membrane of cancer cell. 2) sICAM-1 titers were higher in the HCC group than CAH and LC groups and tended to be increased in proportion to the cancer occupying area, but declined after completing therapy. The result of this study suggest that sICAM-1 is helpful in evaluating TAE therapy and prognosis in HCC.