Effects of vasopressin via V1a- and V2-receptors are closely implicated in a variety of water-retaining diseases and cardiovascular diseases, including heart failure, hyponatraemia, hypertension, renal diseases, syndrome of inappropriate antidiuretic hormone secretion, cirrhosis and ocular hypertension. As vasopressin receptors are found in many different tissues, vasopressin antagonists may benefit the treatment of disorders such as cerebral ischaemia and stroke, Raynaud's disease, dysmenorrhoea and tocolytic treatment. V1b selective vasopressin antagonists are discussed in terms of their usefulness in the treatment of emotional and psychiatric disorders. The vaptans are vasopressin receptor antagonists with V1a (relcovaptan) or V2 (tolvaptan, lixivaptan) selectivity or non-selective activity (conivaptan) which may be advantageous in some disorders. The V1a/V2 non-selective vasopressin antagonist conivaptan is the first vaptan which is approved by the FDA for the treatment of euvolaemic hyponatraemia.