A double-blind, randomized, active drug-controlled study was conducted in order to evaluate the efficacy and safety of famotidine vs ranitidine h.s. in promoting the healing of acute duodenal ulcers. Two hundred and eighty patients participated in the trial and received either famotidine 40mg h.s. or ranitidine, 300mg h.s. The two groups were not significantly different with regard to sex and risk factors such as alcohol consumption and family history of peptic ulcer disease, while in the famotidine group, there was a slightly higher number of patients who smoked. Endoscopy was performed at the end of 4 and 6 weeks in 248 patients (128 in the famotidine group and 120 in the ranitidine group). The healing rate in those receiving famotidine was 73.4% at the end of 4 weeks and increased to 93% at the end of 6 weeks, while in the ranitidine group, the rate was 75.8% and 92.5% respectively. Day and night pain markedly reduced in both groups and therapy was generally well tolerated.