Sonographically guided percutaneous ethanol injection therapy has been used widely in the treatment of hepatocellular carcinoma. However, few reports have been published on the results of this treatment in large numbers of patients. Accordingly, we describe our experience with 146 patients who had this treatment. The study is an update of our previous reports on this subject. We used ethanol injection, with or without transcatheter arterial embolization, 1048 times in 146 patients who had 242 lesions of hepatocellular carcinoma. In 98 patients, ethanol injection was used to attempt a cure of the disease. In the remaining 48 patients, ethanol injection was used palliatively only to reduce the tumor burden. In most cases, 2-8 ml of absolute ethanol was injected in one treatment session. Patients were given the injections two or three times each week until ethanol was injected throughout the lesion. When tumors were greater than 2 cm in diameter, ethanol was injected into the edges of the lesion. Histopathologic examination after treatment in 21 cases showed that the lesion was completely necrotic in 15 cases, 90% necrotic in five cases, and 70% necrotic in the remaining case. Follow-up angiography performed in 69 cases showed no contrast stains in the treated tumors in 60 cases. Elevated serum levels of alpha-fetoprotein decreased in 39 of 43 cases. The 1-, 2-, 3-, 4-, and 5-year survival rates of all 146 patients were 79%, 64%, 46%, 38%, and 38%, respectively. Among 98 patients in whom ethanol injection was used as a potentially curative therapy, these rates were 85%, 70%, 62%, 52%, and 52%, respectively. After ethanol injection, the cancer recurred frequently; the 1-, 2-, 3-, 4-, and 5-year recurrence rates in the potentially curative group were 26%, 38%, 51%, 60%, and 60%, respectively. However, 84% of recurrences were new lesions in different portions of the liver; recurrence of lesions treated by ethanol injection was rare. Major complications of the treatment were peritoneal bleeding in two cases and pleural effusion in one case. Histopathologic examination, angiography, and serum levels of alpha-fetoprotein showed that percutaneous ethanol injection is a valuable treatment of hepatocellular carcinoma. The therapy increased the long-term survival of patients who have this disease.