Bleeding stress ulcus is a mucosal stress induced lesion which appears as a result of mucosal damage in severely injured and critically ill persons. Prophylaxis treatment has dramatically reduced the incidence of bleeding in Intensive care units. We conducted a prospective study for the five years period. Of 954 patients (196 with acute necrotizing pancreatitis and 758 with severe injuries), 84 (8.5%) has clinically important bleeding. About 80% of these patients had more than one independent risk for acute bleeding from gastrointestinal tract. Prophylaxis treatment reduced bleeding in 90% risk patients (according Zinner score). Despite of prophylaxis, 13 patients required surgery. Overall mortality was 29 (34%) of 84 patients, including seven of 13 who required surgery. Sepsis and respiratory failure were identified as strong risk factors for bleeding in our group. The choice of the best prophylactic agens still remains the question.