To study whether or not emergency sclerotherapy was more effective than a program of stabilization and elective sclerosis, we studied 84 patients with bleeding esophageal varices. They underwent 332 sessions of endoscopic injection sclerotherapy, 134 of which were performed for acute variceal bleeding. Most patients (90.5%) had nonalcoholic portal hypertension. Emergency sclerotherapy (1-6 h after presentation) was performed in 65 bleeding episodes in 43 patients, and delayed sclerotherapy (more than 24 h from presentation) was performed in 69 episodes in 41 patients. The selection of patients was randomized. Emergency sclerotherapy arrested active variceal bleeding in all patients and resulted in an earlier eradication of varices and for a longer period than delayed sclerotherapy. Larger volumes of sclerosant (a mean of 26 ml compared to 13 ml) were more effective in arrest of bleeding and in an early eradication of varices. We conclude that emergency sclerotherapy, mainly with a large sclerosant volume, is highly effective in arresting active variceal bleeding. Such earlier arrest of bleeding was associated with reduced morbidity and mortality.