For the purpose of achieving emergency hemostasis of a ruptured hepatocellular carcinoma (HCC) or prevention of such rupture, we applied a new method of transcatheter therapy: intra-arterial alcoholization. Five patients with a ruptured HCC and 42 with an impending rupture were treated by intra-arterial injection of absolute ethanol mixed with an equal volume of iodized oil, Lipiodol (EtOH-Lp). The tumor size ranged from 4 to 26 cm (mean 7.8 cm) in diameter. The catheter tip was placed in the segmental branch or a more distal position of the hepatic artery, and 2-40 (mean 10.6) ml of EtOH-Lp was infused under fluoroscopic guidance. Infiltration of ethanol into the HCC mass was recognized as a dense deposition of Lipiodol on plain abdominal X-rays and computed-tomography. In all five cases of ruptured HCC, hemostasis was achieved. In all 42 cases of impending rupture, tumor rupture was prevented, and all except 3 patients could be discharged. No significant complication of the gastrointestinal tract or biliary tract was seen. The incidence and severity of postembolization syndrome was markedly lower than those seen in cases treated with Gelfoam embolization.