heart failure (HF) is still a major problem worldwide with high morbidity and mortality rates. The recently developed medication for HF is still incapable of reducing its morbidity and mortality, and clinical data supporting the efficacy and safety of its mainstay therapy remain insufficient.Arginine-vasopressin (AVP) plays important roles in circulatory and water homeostasis, one of which is water retention through the V2 receptor. In patients with HF, there is an increased level of AVP, contributing to such symptoms as edema, dyspnea, and congestion. Tolvaptan as a selective V2 receptor antagonist, in addition to the conventional therapy, has been shown to cause an increase in net fluid loss, a decrease in body weight, and a reduction in the rate of HF exacerbation. Such evidence has been provided by the Acute and Chronic Therapeutic Impact of a Vasopressin Antagonist (ACTIV) in Congestive heart failure (CHF), Efficacy of Vasopressin Antagonism in heart failure Outcome Study With Tolvaptan (EVEREST), Acute heart failure Volume Control Multicenter Randomized (AVCMA), and Study of Ascending Levels of Tolvaptan in hyponatremia 1and 2 (SALT-1 and SALT-2) trials. Tolvaptan can be an alternative diuretic in conjunction with other standard therapies for HF and has already been proved to be able to decrease morbidity and mortality, especially in HF patients with hyponatremia.