30 patients with endoscopically proved duodenal peptic ulcer were treated with Bulgarian drug Ranatidin in a dose of 150 mg twice daily in the course of 20 days. The pains were relieved up to the third day in 90% of the patients treated and the dyspeptic complaints disappeared in 1-3 days in 96-100% of the patients. Following the treatment course a statistically significant decrease of the gastric secretion indices was established (V, V1) and of the basic acid production (BAO, MAO, PAO) in comparison with the values before the treatment. Full epithelialization of the ulcer was found endoscopically in 60% of the patients treated and in the remaining 40% the size of the ulcer has diminished. The ulcer epithelialization is related to its initial size. The results achieved do not differ from those achieved with the analogous English drug Zantac. No side effects were observed in the course of treatment with Ranatidin.