Abstract: Objective To investigate the value of ^99mTc-N-NOET(NOET) myocardial perfusion imaging during exercise in the diagnosis of coronary artery disease (CAD), and the relationship between exercise NOET lung/heart ratio and left ventricular diastolic function. Methods Exercise-delayed NOET myocardial perfusion imaging was performed in 49 patients undergoing coronary angiography, among whom 29 had coronary stenosis≥50% and 20 normal coronary artery. Results The sensitivity and specificity of exercise NOET myocardial perfusion imaging were 86.2% and 95.0%, respectively, in the detection of CAD. The NOET lung/heart ratio of CAD patients with multiple branch involvement (0.76±0.13) was significantly higher than those of patients with single branch lesion (0.62±0.06) and with normal coronary artery (0.58±0.13, F=18.04, P=0.002-0.001). When the lung/heart ratio was over 0.70, the sensitivity and specificity of the imaging for detecting the presence of multiple branch involvement were 93.5% and 83.3%, respectively. NOET lung/heart ratio showed a significant correlation with E/A ratio (r=-0.771, P<0.000 1). Conclusion Exercise NOET lung/heart ratios has diagnostic values for multiple branch lesions and left ventricular diastolic function abnormalities in patients with CAD.