The aim of the present investigation was to study the efficacy and safety of famotidine (MK-208), a new, potent, histamine H2 receptor antagonist, in promoting the healing of active gastric ulcer when compared to placebo. Of the 71 patients who took part in this multicenter double-blind study in Italy, 37 were administered famotidine 40 mg once daily and 34 placebo. Treatment duration was for up to 8 weeks, and endoscopic and clinical studies were performed at onset and week 4 and, if necessary, at weeks 6 and 8. All patients were carefully evaluated at regular intervals for adverse drug reactions by clinical and laboratory examinations. By the end of the study, 97% of the ulcers were healed in the famotidine group compared to 66% in the placebo group (p less than 0.01). Day and night pain decreased significantly more in the famotidine group than in the placebo group. Both treatments were well tolerated, and no alterations in laboratory tests were observed. Famotidine, therefore, proved effective in the treatment of gastric ulcer and was well tolerated on a short-term basis.