Upper GI bleeding is a common medical emergency with an incidence in the UK of 103 cases per 100,000 adults per year and is much more common in the elderly. The most common presenting signs are haematemesis (bright red or 'coffee ground') and melaena. About 30% of patients with bleeding ulcers present with haematemesis, 20% with melaena, and 50% with both. Up to 5% of patients with bleeding ulcers have haematochezia and this indicates heavy bleeding into the upper GI tract. An upper GI bleeding source should be considered when haematochezia presents with signs and symptoms of haemodynamic compromise. Peptic ulcer disease, both gastric and duodenal, accounts for the majority of admissions for upper GI bleeding. Other causes of bleeding include mucosal (Mallory-Weiss) tear of the gastro-oesophageal junction secondary to vomiting, and multiple types of vascular abnormalities. Clinical risk factors for mortality in upper GI bleeding are age, comorbidity, tachycardia and a low systolic blood pressure. Given the high mortality rate associated with upper GI bleeding nearly all patients with symptoms described above should be referred to secondary care for emergency admission and endoscopic assessment. This should also be the default position in borderline cases. Early endoscopy in upper GI bleeding: allows early diagnosis; provides the opportunity for endoscopic haemostasis; enables complete risk stratification of non-variceal bleeding and allows early discharge of patients with low-risk findings.