Complex neurohormonal interactions dictate the body's volume status in different disease states. Besides the known pathologic activation of the renin-angiotensin-aldosterone axis and the effect of the adrenergic system, arginine vasopressin (AVP) represents a key element that is responsible for volume homeostasis. Serum AVP levels have been shown to be chronically elevated in different pathologic conditions that exhibit an imbalance in volume status, particularly in congestive heart failure. Evidently, elevated levels of AVP play an important role in the pathogenesis and progression of these diseases. AVP has many other receptor-mediated deleterious effects on vascular smooth muscles and cardiomyocytes. These effects are an integral part of the neurohormonal milieu in patients with heart failure. This assumption has propelled agents that antagonize the effects of vasopressin receptors to the forefront of clinical research, especially in heart failure management. This paper reviews current knowledge on conivaptan, a novel dual V1a/V2 vasopressin receptor antagonist.