BACKGROUND Acute upper gastrointestinal tract bleeding is a cause of significant morbidity and mortality and is a reason for urgent endoscopy. Besides an age and associated diseases, prognosis of patients influence also localisation and type of bleeding. The aim of our retrospective analysis was to discover causes of bleeding into upper GI tract and its characteristics over a 4 year period. METHODS A survey of urgent upper GI tract endoscopies in the Clinic of Internal Medicine in Motol in Prague because of an acute GI tract bleeding (hematemesis or melena) was done. Found ulcers were assessed using Forrest classification. Moreover, number and causes of recurrences of bleeding were also assessed. RESULTS Within years 1998-2001 an urgent upper GI endoscopy because of bleeding (hematemesis or melena) was done in the Clinic of Internal Medicine in Prague in Motol in 1639 patients of an average age 62.2. 56% were men (average age 59) and 44% were women (average age 65.3). An endoscopy finding without pathology was present in 21.4%. The most frequent sources of bleeding were ulcers in duodenal bulb (20%), stomach ulcers (18.2%), and hemorrhagic gastropathy (16.5%) and varices (10.3%). Results of the Forrest classification in the ulcerative disease of stomach and duodenum were as follows: Forrest Ia 9.5%, Ib 24%, IIa 14.6%, IIb 18.7%, IIc 22.9%, III 10.3%. Recurrent bleeding was identified in 8.4% of patients, thereof bleeding from esophageal varices experienced 2.9% of patients (average age 45.8), bleeding from ulcers in bulbus 2.7% (Forrest Ib, IIa a IIb) of patients of an average age 62.6, and bleeding from ulcers in stomach 2.1% (Forrest Ia, IIa a Ib) of patients of an average age 62.5. Causes of recurrent bleeding were in one case bleeding from Barrett's oesophageal ulcer and in one case bleeding from ulcer in diaphragmatic hernia. Within 48 hours recurrent bleeding appeared in 65% of patients. CONCLUSIONS Urgent endoscopy in gastrointestinal tract bleeding is an essential part of a complex medical care. It is highly reliable in identifying cause of bleeding, it enables to start treatment immediately and to consider prognosis of a patient.