Recent studies have shown that the prophylactic use of H2-receptor antagonists reduces both ulcer recurrence and the risk of ulcer complications. Despite these results, epidemiological studies have failed to show any evidence of an effect of gastric anti-secretory drugs on complicated ulcer disease in the community. Since 1979, it has been the policy of the gastroenterology department at Ninewells Hospital in Tayside to recommend long-term, continuous therapy with H2-receptor antagonists for patients with peptic ulcer; in contrast, prophylactic therapy is less commonly used in the rest of Scotland. The difference in the management of peptic ulcer between Tayside and Scotland presented an opportunity to study the population effects of the widespread use of continuous H2-receptor antagonists on the morbidity and mortality from ulcer disease. This study compared the trends in hospital admissions, gastric surgery, haemorrhage, perforation and mortality from ulcer disease using data supplied by the Information and Statistics Division of the Common Services Agency, Scottish Health Service, Edinburgh. During the 1980s, hospital admissions for peptic ulcer declined significantly in Tayside, whereas in Scotland there was no obvious downward trend. Gastric surgery for ulcer disease declined throughout Scotland although the fall was significantly steeper in Tayside than in the rest of Scotland. For the population in general, the rate of perforation decreased faster in Tayside than in the rest of Scotland, although the difference was not significant. The rate of admissions for ulcer haemorrhage declined substantially in Tayside whereas there was little change in Scotland as a whole. The decrease in mortality from ulcer disease in all groups except younger females was more marked in Tayside than in Scotland, although the differences were not significant. The magnitude of the differences between Tayside and Scotland, and in particular the consistency of these results across a broad range of indicators of ulcer disease, suggests that the policy of prescribing long-term, continuous therapy with H2-receptor antagonists has reduced both uncomplicated and complicated peptic ulcer in the community in Tayside.