Clinical, endoscopic, and laboratory data were collected prospectively in 701 patients with bleeding peptic ulcer. The overall rebleeding rate was 16.1% and increased the risk of a fatal outcome by 17 fold (1.2% versus 20.6%, p< 0.001). Rebleeding was documented in more than 75% of the group who did not survive following initial conservative management. Rebleeding was more likely (24.1% versus 14.2%, p< 0.02) when shock was present on admission and the risk of a rebleed was doubled in patients over 60 years of age (22.1% versus 10.9%, p< 0.001). Ulcers greater than 1 cm in size carried twice the risk of rebleeding (23.9% versus 12.4%, p< 0.002). Concomitant medical illness had a significant adverse effect on outcome (p< 0.05). Shock on admission was associated with a doubling of mortality figures (9.5% versus 3.7%, p< 0.01). The identification of endoscopic stigmata of recent hemorrhage (ESRH) tripled the risk of mortality (7.5% versus 2.4%, p< 0.002), ESRH were more frequently encountered when ulcer size was larger than 1 cm (61.4% versus 39.8%, p< 0.001). Respective mortality rates for ulcers less than or equal to 1 cm and greater than 1 cm in size were 1.6% and 12.5% (p< 0.001), corresponding mortality figures for patients over 60 years of age being 4.4% and 16.4% (p< 0.002). The risk of a rebleed tripled (6.7% versus 2.6%, p< 0.02) when ESRH were evident. There was a 6-fold increase in mortality following emergency surgery when compared with conservative management of patients in whom no surgical intervention was necessary (2.6% versus 14.9%, p< 0.001). In summary, age over 60 years, previous medical illness, shock on admission, large ulcer size, and ESRH were each associated with an increased risk of rebleeding and mortality. © 1990 Société Internationale de Chirurgie.