The number of perforated duodenal ulcers at five Seattle-area hospitals and all duodenal ulcer operations performed at three Seattle-area hospitals were studied. In the past ten years, a decline of 35% in both perforated duodenal ulcers and all duodenal ulcer surgery indicates a similar decline in the overall incidence of duodenal ulcer. These data are supported by articles in the literature, which report a declining incidence of duodenal ulcer beginning around 1955 and continuing for 20 years. This decline challenges the idea that duodenal ulcer results chiefly from the stresses of urbanization.