We designed a prospective randomized study to evaluate differences in efficacy and complication rate between the two most commonly used sclerosing agents, sodium tetradecyl sulfate (STD) and sodium morrhuate (MOR). Of 41 patients with acute index variceal bleeding initially evaluated, 21 were randomized to receive 0.75% STD and 20 to receive 1.6% MOR diluted with 50% dextrose. Overall mortality for the STD group was 38% and that for the MOR group was 25% (NS). Control of acute bleeding was achieved in 86% of the STD patients and 90% of the MOR patients (NS). Overall, obliteration was achieved in only 33% of the STD group and 25% of the MOR group; but in those patients who remained in the study over 3 months, obliteration was achieved in 87 and 83%, respectively (NS). There was a trend toward higher rebleeding in the STD group compared with the MOR group (81% vs. 51%) (p = 0.078), but there was no significant difference between the STD and MOR patients with regard to transfusion requirements (8.4 units/patient vs. 8.7 units/patient), ulceration (53% vs. 40%), or stricture formation (9.5% vs. 0.0%). The results of this study suggest that STD and MOR are clinically equivalent sclerosing solutions, and that bias favoring use of one agent over the other may be unfounded.