Forskolin, a diterpene derivative of the Indian plant Coleus forskhohlii, proved to be a marked positive inotropic and vasodilatory compound in animal experiments with a mechanism of action distinct from catecholamines, cardiac glycosides, and phosphodiesterase-inhibiting compounds. The cardiovascular effects of forskolin seem to be mediated by a direct stimulatory action at the catalytic unit of sarcolemmal adenylate cyclase. The aim of the present study was to clarify the cardiovascular profile of this compound in 12 patients with stage III (NYHA) congestive cardiomyopathy. The effects of forskolin were investigated by invasive techniques using the thermodilution catheter method and compared to the beta 1-receptor agonist dobutamine and the vasodilator sodium nitroprusside in an intraindividual comparison. Forskolin dose-dependently reduced cardiac pre- and afterload values, and led to a reduction in systolic, diastolic, and mean pulmonary artery pressure as well as pulmonary wedge pressure by greater than 50% concomitant with an increase in cardiac output. There was a slight increase in heart rate. Cardiac stroke volume and stroke volume index was increased by approximately 70%. The cardiovascular effects of dobutamine and nitroprusside were less pronounced; however, it seemed that a similar hemodynamic profile could be achieved by the combination of both dobutamine and sodium nitroprusside. In view of the rapid development of tolerance toward beta 1-receptor stimulation, forskolin, with its receptor-independent mechanism of action, may be advantageous for the treatment of severe heart failure, especially in patients with catecholamine-insensitive heart failure.