Introduction: Exercise test (ET) is the first line of ischemia assessment in patients with suspected Coronary Artery Disease (CAD). We conducted this study to evaluate whether Major Depressive Disorder (MDD) influences the parameters of ET performance and affects the interpretation of test results.Material and Methods: In an ex-post facto study, 265 patients (191 Men, 74 women; mean age 48±10 years, 22-75 years old) referred for ET were enrolled through convenient sampling after completing and signing informed consent forms. After exercise testing, Beck Depression Inventory (BDI) was used to assess depression. Data was analyzed using t- paired, k2 and correlation coefficient tests under SPSS10 software.Results: The prevalence of depression was 41.5%. The proportion of positive ET in depressed and non-depressed groups was 23.6% and 19.4% respectively (p>0.05). After adjustment for age, sex, family history of CAD, and smoking habit, total exercise duration showed negative correlation with BDI scores (p<0.001). Correlation analysis for Maximum Predicted Heart Rate showed a strong trend of negative relation (p=0.06). Duration of performing ET was significantly lower in MDD patients (p=0.001).Negative correlation of BDI with ET performing duration was true both before and after corrections for the mentioned variables (p=0.001).Conclusion: Decreased psychomotor activity in depression may lead to inadequate exercise duration and affect the performance indices. However, if the performance indices of ET in a depressed patient are acceptable, the test result could be interpreted with confidence.