Introduction: Erectile dysfunction (ED) and coronary artery disease (CAD) are closely related as a result of endothelial dysfunction leading to the restriction of blood flow. ED is a potential independent risk factor of CAD. We investigated the prevalence and severity of ED, the extent of CAD and the time interval between the symptoms of ED and CAD in the stable coronary artery patients. Materials and methods: 161 patients applied coronary angiography were divided into two groups according to SYNTAX score as group 1 (n=81) SYNTAX score <= 22, and group 2 (n=80) SYNTAX score >22. The prevalence and severity of ED was determined by using The International Index of Erectile Function (IIEF). Results: The prevalence of ED was 43.2% in group 1 and 61.3% in group 2 (P=0.022). The score of IIEF was 23.1 (15-29) in group 1, 19.3 (6-29) in group 2; there was a significant difference (P=0.000). In the multivariate logistic regression analysis carried out in order to determine the independent predictors on Syntax score, it was found that LDL (odds ratio: 1.032, 95% confidence interval: 1.009-1.055, P=0.007) and IIEF score (odds ratio: 0.825, 95% confidence interval: 0.733-0.928, P=0.001) were the independent predictors. The time between the symptoms of ED and CAD 30.1 +/- 4.8 months in group 1, and 40.5 +/- 4.3 months in group 2 (P=0.000). Conclusion: The severity of ED is an independent factor predicting the extent of CAD. The early detection of ED enables to make a cardiovascular evaluation. Therefore, taking the cardiovascular risk factors under an aggressive treatment may contribute to prevent the cardiovascular cases which may develop in the future.