Background: We aimed to identify the clinical and echocardiographic factors related to false results in the exercise tolerance test (ETT). Methods: The present study included all patients who underwent transthoracic echocardiography and the ETT, followed by coronary angiography, within 6 months prior to echocardiography between March 2008 and March 2013. Clinical, 12-lead resting ECG, ETT, transthoracic echocardiography, and coronary angiography data were extracted. The multivariable logistic regression analysis was used to investigate the independent predictors of the false results of the ETT. Results: Totally, 4057 patients, who underwent transthoracic echocardiography, ETT, and angiography, were enrolled. 1132 patients with no significant coronary stenosis on angiography, 979 (84%) had false-positive results in the ETT and 153 (14%) had true- negative ETT results. In patients with significant coronary artery disease (CAD), there were 2728 (93%) true-positive and 197 (7%) false-negative ETT results. In our univariate analysis, the patients with false ETT results were more likely to be female and younger than the group with true ETT results. In our multivariable model, female gender increased and right bundle branch block and dilated left ventricular diastolic internal dimension (LVID) decreased the likelihood of a false-positive result in the ETT. The probability of a false- negative result in the ETT was increased by resting ECG changes, hemiblocks, and dilated LVID. Conclusions: The diagnostic value of the ETT in patients with suspected CAD should be adjusted according to sex, presence of resting ECG changes, CAD risk factors, and traditional echocardiographic measurements. A dilated LV increases the risk of false-negative results and decreases the likelihood of a false-positive result in the ETT. (Iranian Heart Journal 2016; 17(3):36-45)