PURPOSE: To evaluate histopathologic change in the liver after injection of various kinds of sclerosants, andto thus determine whether 50% acetic acid, a new sclerosant, is suitable for percutaneous intrahepatic injection. MATERIALS AND METHODS: Four kinds of clinically available sclerosants were used : 50% acetic acid, 99% ethanol,10% phenol, and hot saline. Each group consisted of ten rats, and 0.1ml of each sclerosant was directly injectedinto the liver. After two days and one week, gross and histopathologic findings of resected liver in the area oftissue necrosis, as well as the degree of extrahepatic peritoneal adhesion, were assessed in each group. RESULTS:In all groups, the main pathologic changes were acute necrosis with inflammation after two days and secondaryregenerative fibrosis after week. In the 50% acetic acid injection group, the degree of necrosis was more severeand the mean diameter of the necrotic area was greater ; this latter was not, however, significantly wider than inthe 99% ethanol injection group, though was significantly wider than in the 10% phenol and hot saline injectiongroup. CONCLUSION: When used for percutaneous injection, 50% acetic acid, caused more tissue necrosis than 99%ethanol, 10% phenol, or hot saline. We therefore conclude that this acid may be useful for percutaneousintrahepatic injection of a hepatic tumor.