To evaluate the hemodynamic effects of nifedipine on anginal patients during exercise in the upright position, a placebo (P) and 20 mg of nifedipine were administered in a double-blind random sequence to ten patients presenting with exertional angina and a healed myocardial infarction. All patients had previously undergone coronary angiography. The effects of nifedipine in the upright position at rest, at the anginal threshold, and at the maximal level of exercise were studied. Nifedipine decreased systemic vascular resistances in upright position and increased the cardiac index. It reduced the severity of angina and allowed a higher physical work capacity without anginal symptoms. The most important beneficial effect of nifedipine appears to be the reduction in afterload, but an improvement of left ventricular function cannot be ruled out.