Selective segmental sclerotherapy of the liver by transportal ethanol injection (SSS) was devised and evaluated in a case of hepatocellular carcinoma. The patient was a 72-year-old man suffering from unresectable hepatoma. Injected ethanol with an amount of 20 ml into the portal branch under occluding the portal flow by balloon catheter produced complete necrosis of the liver proportional to the injected liver segment including the tumor on CT. Because of ethanol perfusion into sinusoid level by wedge injection, its cytotoxicity maybe affected liver cells directly. In this case, there has been no evidence of inadvertent liver damage and a significant rise in the blood ethanol level. The present technique of SSS in this clinical case and our past animal experience seemed to yield the same condition as resection without surgical disadvantages and be apparently a safe method, which is suggested for clinical use for several hepatic tumors.