In the treatment of gastroduodenal ulceration both the reduction of gastric acidity and the defence of mucosal membrane have an important role. The development of H2-receptor antagonist has brought a significant change in the decrease of acid secretion in the last two decades. After the development and clinical application of cimetidine and ranitidine, a newly developed H2-receptor blocker, the famotidine has been introduced. Both the pharmacological and clinical investigations demonstrated the efficacy of this drug either in gastric or in duodenal ulcerations. The clinical pharmacological studies expressed mainly the advantageous character, that in the achievement of therapeutic effect smaller quantity is required than that of the other H2-receptor blocker. In the dosage of 40 mg (bedtime once, or daily twice) significantly decreases the basal and the stimulated gastric acid secretion as well as the daily and the nocturnal pains of the patients. Experience for several years have demonstrated efficacy in a 20 mg dosage of this drug in defence of ulceration relapses. It can be very well tolerated without significant side effects. Its long term applications is safety and economically advantageous.