Three open-label, uncontrolled studies have documented successful treatment of warts with cimetidine, whereas two placebo-controlled, double-blind studies and two open-label comparative trials have failed to demonstrate efficacy. This double-blind, placebo-controlled study was designed with stringent enrollment and outcome criteria to minimize the confounding issue of spontaneous remission. Efficacy was not statistically superior to that of placebo, but a trend toward efficacy was suggested for younger subjects.