Olprinone, a phosphodiesterase (PDE) 3 inhibitor, is used to treat heart failure due to its positive inotropic and vasodilative effects. Selective inhibition of the PDE 3 isozyme increases intracellular adenosine 35-cyclic monophosphate and enhances Ca2+ influx into cardiac muscle cells. The most significant advantage of PDE 3 inhibitors is their ability not only to enhance myocardial contraction, but to reduce, through vasodilatory action, the stress to which the heart is subjected. In peripheral vessels, the decrease of cytosolic free Ca2+ induces the vasorelaxation of vascular smooth muscle cells. In this way, olprinone reduces mean aortic and pulmonary artery pressures. Additionally, olprinone exerts differential vasodilatory effects on peripheral vessels in each organ, based on the differences in the distribution of PDE 3 among the organs. With respect to the cerebral circulation, olprinone augments blood flow in the cerebral cortex through direct vasodilatory effects on small cerebral arter ies or arterioles. Olprinone increases hepatosplanchnic blood flow and improves oxygen supply. While long-term therapy with PDE 3 inhibitors in patients with chronic heart failure may accelerate the progress of the underlying disease and provoke serious ventricular arrhythmia, olprinone shows good potential for short-term treatment in patients who have experienced severe heart failure or patients who have undergone cardiac surgery.