The present study has attempted to determine the prevalence of peptic ulcer (UP) in smokers and nonsmokers in the geographic region of Aragon (Spain) using a sample of 10,000 subjects, 1,897 with ulcer, 1,708 of them diagnosed by endoscopy. The prevalence of smokers is 42.4% (63% of males and 14% of females). The prevalence of peptic ulcer in smokers (26.87%) is double that of nonsmokers (13.38%) (p less than 0.05). In males, all of the locations (duodenal, duodenal + gastric and gastric) are more common among smokers than among nonsmokers. These differences do not exist in women, gastric ulcer being more common among nonsmokers. Complications were more frequent among smokers with ulcer (60%) than among nonsmokers with ulcer (40%).