Inappropriate increases in vasopressin contribute to water retention in heart failure. Therefore, vasopressin receptor blockade with tolvaptan represents a potential therapeutic intervention in heart failure. The EVEREST trial reported in the NEJM evaluated the use of tolvaptan versus placebo in patients with decompensated acute heart failure. However, in the EVEREST trial treatment with tolvaptan versus placebo showed no difference in long term mortality or heart failure morbidity in patients with decompensated acute heart failure. Tolvaptan’s utility in chronic heart failure is still under investigation.