Forty-seven patients with coronary artery disease characterized by angina pectoris and/or old myocardial infarction underwent two maximal exercise tests, the supine ergometer test and the upright treadmill test, to study the relationship between exercise capacity and exercise hemodynamics. Subjects were divided into 3 groups: Group I (n = 19) achieved 25 or 50 watts, Group II (n = 15) achieved 75 watts and Group III (n = 13) achieved 100 or 125 watts. During ergometer exercise, the mean pulmonary capillary pressure elevated by 25.3 +/- 8.3 mmHg in Group I, 20.8 +/- 8.8 mmHg in Group II and 12.0 +/- 8.4 mmHg in Group III; the Group III value was significantly smaller than the other groups. The stroke volume index decreased by 3.6 +/- 8.8 ml/m2 in Group I, and increased by 10.9 +/- 8.7 ml/m2 in Group II and 10.7 +/- 14.7 ml/m2 in Group III. Thus, the impaired exercise capacity correlated with the abnormal exercise hemodynamics and its severity. In addition, the exercise capacity in the treadmill test was comparable to that in the ergometer test. It was concluded that the impaired exercise capacity in the both supine and upright exercise tests was well related to the development of abnormal exercise hemodynamics in patients with coronary artery disease.