The histamine H2-receptor antagonists, cimetidine, ranitidine, famotidine and nizatidine are effective in promoting the healing of both gastric and duodenal ulcer. Unfortunately the recurrence rate after withdrawal of the therapy does not appear modified and many studies indicate an increased rate of relapse after antisecretory treatment. The difference between various H2-blockers in terms of duration of acid inhibition and then increasing in gastrin levels may play a role in explaining the phenomenon, the exception represented by the last H2-blocker, nizatidine. It is reasonable, therefore, to analyze the different therapeutical approaches proposed for ulcer relapse prevention, such as continuous maintenance therapy, seasonal on demand, intermittent, week-end therapy, association of drugs with different mechanisms of action, etc. Four categories of patients can be characterized both for gastric and duodenal localization: 1. Subjects with low rate of relapses, i.e. less than one each fifteen months; 2. Subjects with episodic relapses, i.e.; one or two per year; 3. Subjects with frequent relapses, i.e. more than three per year; 4. Subjects with complications (bleeding, perforation).