Hyponatremia in critically ill patients is a common and challenging problem. Increased levels of arginine vasopressin almost always contribute to the etiology. Inhibition of the vasopressin receptor with a vasopressin receptor antagonist (vaptan) is a novel approach to the treatment of hyponatremia. Vaptans are well suited to the treatment of chronic hyponatremia associated with syndrome of inappropriate anti-diuretic hormone secretion (SIADH) and hypervolemic states like cirrhosis or congestive heart failure. No data are available on the use of vaptans in acute hyponatremia, and they are not indicated in hypovolemic hyponatremia. The focus of this review is the treatment of critically ill patients with hyponatremia with vaptans and other measures.