Nesiritide (human recombinant B-type natriuretic peptide) binds to receptors in the vasculature, kidney, and other organs to mimic the actions of endogenous natriuretic peptides. Intravenous infusion of nesiritide has been studied in more than 1,700 patients with acute decompensated heart failure (HF). Nesiritide causes potent, dose-related vasodilation that is rapid in onset and sustained for the duration of drug infusion. There is balanced arterial and venous dilation as reflected by decreases in systemic vascular resistance, systemic arterial pressure, pulmonary capillary wedge pressure, right atrial pressure, and mean pulmonary arterial pressure. Vasodilation occurs without a change in heart rate and is associated with increases in stroke volume and cardiac output. Nesiritide may promote diuresis because of a direct natriuretic action, increased cardiac output, and/or decreased aldosterone levels. In patients hospitalized for decompensated HF, nesiritide improves symptoms and is well tolerated. The major adverse effect is dose-related hypotension. Nesiritide is thus an attractive new vasodilator that should be valuable in the treatment of patients hospitalized for acute decompensated HF.