Acute upper gastrointestinal bleeding is a common medical emergency which carries hospital mortality in excess of 10%. The most important causes are peptic ulcer and varices. Varices are treated by endoscopic band ligation or injection sclerotherapy and management of the underlying liver disease. Ulcers with major stigmata are treated by injection with dilute adrenaline, thrombin, or fibrin glue; application of heat using the heater probe, multipolar electrocoagulation, or Argon plasma coagulation; or endoclips. Intravenous omeprazole reduces the risk of re-bleeding in ulcer patients undergoing endoscopic therapy. Repeat endoscopic therapy or operative surgery are required if bleeding recurs.