Vasodilatory hypotension requiring the administration of catecholamine pressors may occur following cardiopulmonary bypass. We investigated the hemodynamic response to arginine vasopressin (AVP) in 20 patients who developed vasodilatory hypotension after cardiac transplantation. In this cohort, AVP infusion (0.1 U/min) significantly increased mean arterial pressure and decreased norepinephrine requirements, allowing rapid discontinuation of norepinephrine infusions in 7 patients. Judicious use of this novel agent in appropriately selected patients may minimize end-organ sequelae of hypotension and high-dose catecholamine therapy.