The present study of the prognosis in peptic ulcer comprises an analysis of deaths caused by the disease itself and an independent actuarial analysis of life expectancy. The computations are based on 235 deaths that occurred among 1905 patients with peptic ulcer who constituted a random sample of the occurrence of ulcer disease in an area of Denmark comprising 500,000 inhabitants. The 2 methods of analysis showed that peptic ulcer does influence the survival, but the excess of deaths was small and, in the case of solitary peptic ulcer, was present only in the 1st yr or 2 after the diagnosis. The prognosis tended to be more serious in gastric ulcer than in duodenal ulcer, but the difference was not significant. In duodenal ulcer the survival tended to be better when only a deformed bulb was present. The life expectancy was not significantly different for men and women. Patients with combined gastric and duodenal ulcers had a fatality twice as great as those with solitary ulcers. No excess of deaths was found in patients under the age of 50 yr at diagnosis. The duration of prediagnostic symptoms was not predictive for the prognosis.