Over a 1-yr period, all consecutive patients with upper gastrointestinal hemorrhage from the stomach or duodenum were studied for H. pylori infection by serology. Additionally, the need for mechanical ventilation over 48 hrs, the duration cardiopulmonary bypass, and the aortic cross-clamp time were analyzed. For control, 229 patients with no evidence of gastrointestinal hemorrhage after cardiac surgery were studied. All patients received stress ulcer prophylaxis with ranitidine