Congestive heart failure is a clinical syndrome in which the capacity of the heart to maintain cardiac output is impaired. As a consequence, blood pressure is threatened and endocrine and paracrine mechanisms are activated to preserve circulatory homeostasis and to maintain blood pressure. At terminal stages, a complex multiorgan syndrome develops with severe pump failure, intense systemic vasoconstriction, and avid water and sodium retention. Increasing evidence points to humoral circulating or locally synthesized substances as one of the causes of the terminal consequences of heart failure. Therefore, the hypothesis that the syndrome of heart failure is, at least in part, a humoral disease has developed and is obtaining scientific credibility. Consequently, the neuroendocrine response to heart failure is no longer viewed as a compensatory beneficial mechanism. Instead, we have learned through the years that pharmacological treatment aimed at reducing the effect of the neuroendocrine response is indeed clinically and prognostically advantageous for the patient.