The majority of patients with cirrhosis will develop varices during their lifetime. At least a third of these patients will bleed from their varices and despite significant improvements in treatment and diagnosis of first variceal haemorrhage, the mortality still remains high (30%). Patients with a high risk of bleeding need to be identified, in order to define a group who will benefit from primary prophylaxis. The most important predictors of oesophageal variceal bleeding are variceal size, presence of red wale markings and severity of liver dysfunction as defined by Child-Pugh score. These and other factors have been combined in prognostic indices in an effort to predict those patients most at risk of variceal haemorrhage. In recent trials, variceal size was found to be the most important predictor of variceal bleeding and therefore is the variable used to decide whether a patient should receive primary prophylaxis. Variceal size, location (fundus), Child-Pugh score are all associated with a higher risk of bleeding from gastric varices.