Background: Assessing right ventricle (RV) function is difficult primarily because of its complex shape. Worsening RV function or dilatation during stress tests in patients with coronary artery disease may indicate proximal right coronary artery (RCA) narrowing. The aim of this study was to obtain quantitative diagnostic criteria for impaired RV function by tissue Doppler imaging (TDI) during exercise echocardiography, which could detect a significant lesion of the RCA in patients with coronary artery disease. Methods AND Results: We evaluated regional systolic and diastolic function using pulsed-wave TDI in two myocardial segments of the RV free wall during exercise stress tests in 160 patients with suspected coronary artery disease. The diagnostic criteria were obtained by comparing TDI and coronary angiography data. The accuracy, sensitivity, and specificity of the TDI diagnostic model for RCA disease were 81.1, 88.0, and 72.3%, respectively. Conclusion: TDI is a highly accurate method for the detection of RV dysfunction and RCA disease at rest and during exercise stress echocardiography in group of patients with known or suspected coronary artery disease.