To assess acute hemodynamic effects of the new beta-adrenergic blocking drug bisoprolol with experimentally documented beta 1 selectivity, we studied 16 patients with stable angina and angiographically proven coronary artery disease. Simultaneous right heart catheterization and radionuclide angiocardiography were performed at rest and during exercise without treatment (control) and 2 h after 5 mg bisoprolol (6 patients) and 20 mg bisoprolol (10 patients), respectively, administered perorally. The hemodynamic profile of bisoprolol was similar to that previously described after acute beta-blockade. A negative chronotropic effect occurred after 5 mg bisoprolol at rest, but the negative inotropic changes did not reach significance, whereas cardiac index decreased and total vascular resistance increased after 20 mg bisoprolol. During exercise, negative inotropic and blood-pressure-lowering effects were present after both dosages, resulting in improved myocardial oxygen consumption as reflected by a significantly reduced rate pressure product. Because ejection fraction and pulmonary capillary wedge pressure were not significantly changed even after the 20 mg dose, bisoprolol has only mild negative inotropic effects and seems hemodynamically safe.