In a preoperative evaluation, 35 consecutive patients with aortic stenosis were examined by means of exercise ECG, Doppler and direct manometric measurements of the pressure difference over the aortic valve (delta P) and angiocardiography. Coronary artery disease (CAD) was found in 43% of the patients. Those with CAD had a lower mean maximum physical performance expressed as a percentage of the normal value (Wmax%), larger ST depressions and a higher effort angina (EA) score at the exercise test than the non-CAD group. Mean delta P was equal in the two groups. A myocardial coronary obstruction score covariated positively with a coronary insufficiency index (CT index = 100 X STdepr/Wmax%) and the EA score. There was no correlation between delta P and the EA score or the CI index. A CI index less than 3 and an EA score less than 2 were found in 49% of the patients and excluded the presence of CAD with a predictive accuracy of 88%, a better diagnostic complement to coronary arteriography than a history of EA.