The value of an abnormal ratio of recovery systolic blood pressure to peak exercise SBP for detecting coronary artery diseases (CAD) is controversial. We evaluated the ratio in 39 patients with angiographically documented CAD and 52 patients with normal coronary artery undergoing treadmill exercise. If a response with the ratio higher than 1.0 and 0.8 at 1 and 3 min. of recovery was considered as abnormal, the sensitivity for detecting CAD was 66.7%, the specificity 73.1% and the accuracy 70.3%. If ST segment depression is combined into the criteria, the specificity and accuracy reach 94.2% and 76.9%. In CAD, the ratio at 3 min. of recovery showed significant negative correlation with resting left ventricular ejection fraction (LVEF) (r = -0.461, P < 0.01). It is suggested that low resting LVEF may be one of the mechanism of this abnormal ratio in CAD.