Coronary angiography was performed in 250 patients with a significant ischemic ST segment change detected by symptom-limited maximum treadmill exercise testing, and relationship between anatomical severity of coronary artery disease and parameters in exercise testing was studied. The age of the patients ranged from 34 to 76 years (188 men, 62 women). One-vessel disease (1VD) was presented in 82 patients, two-vessel disease (2VD) in 42, three-vessel disease or left main coronary disease (3VD) in 26, and no significant stenosis was presented in 100 subjects (Normal). Functional aerobic impairement (FAI) was evaluated in each group as a parameter of exercise capacity, myocardial aerobic impairment (MAI) and heart rate impairment (HRI) were also evaluated as a parameter of maximum myocardial oxygen requirements and maximum heart rate, respectively. Using these parameters, discriminant analysis was performed to compare the group with significant coronary artery disease and the Normal group. Also, to compare the group with multi-vessel disease and the group with less than 2VD. Also, the 3VD group and the group with less than 3VD. FAI, MAI and HRI were significantly different (p less than 0.0001) in each group. The discriminant formula to separate the group of significant coronary artery disease from the Normal group was Z = -1.049 + 0.02 [FAI] +0.08 [MAI] +0.03 [HRI]. According to this formula, sensitivity was 92.5% and specificity was 71.5%. The discriminant formula to separate the group with multi-vessel disease from the group with less than 2VD was Z = -4.731 + 0.07 [FAI] +0.106 [MAI] +0.02 [HRI]. According to this formula, sensitivity was 96.3% and specificity was 78.8%.(ABSTRACT TRUNCATED AT 250 WORDS)