Vasopressin is a potent vasoconstrictor which greatly reduces mesenteric blood flow. In patients with portal hypertension this results in decreased portal venous flow and portal pressure. Because of this property, vasopressin has been used for years in the therapy of variceal haemorrhage. A few controlled trials show that vasopressin causes a decrease in bleeding but has no effect on survival. It has been shown that intravenous vasopressin is just as effective as intra-arterial, and is associated with fewer complications.The inability to influence the outcome of variceal haemorrhage significantly may be related to suboptimal dosing due to the occurrence of systemic complications at higher doses. The combination of vasopressin with either sodium nitroprusside or nitroglycerin (glyceryl trinitrate) has resulted in a further decline of portal pressure, along with amelioration of most of the adverse haemodynamic effects of vasopressin. Whether or not clinical efficacy is increased when vasopressin is combined with sodium nitroprusside or nitroglycerin remains to be proven.Analogues of vasopressin, such as terlipressin, held early promise as agents which would be as effective as vasopressin, without the cardiac adverse effects. Recent data have not supported this and at present there is little to suggest any advantage of terli-pressin over vasopressin.Virtually no adequate studies have yet been performed to support the use of vasopressin in the treatment of non-variceal haemorrhages. There is reason to suspect that vasopressin can effectively control bleeding from haemorrhagic gastritis, but the subsequent results of inducing gastric ischaemia in an already damaged gastric mucosa are unknown.In summary, vasopressin appears to have little effect on the mortality of patients with variceal haemorrhage. It may, however, help control the haemorrhage in some patients by lowering the portal pressure. Cardiovascular complications limit the dose that can be used but it is hoped that by combining vasopressin with nitroglycerin, a more effective and safe therapy will be available for variceal haemorrhages.