Objective: Coronary artery ectasia (CAE) is defined as local or generalized aneurysmal dilatation of the coronary arteries. We aimed to determine the frequency of CAE at our center and to compare clinical and angiographic characteristics between patients with isolated CAE and CAE with coronary artery disease (CAD). Methods: From February 2004 to December 2005, 12.514 patients were retrospectively analyzed by two independent operators who underwent coronary angiography. Coronary artery diameters were measured using qualitative computed angiography. CAD risk factors were recorded for all patients. Unpaired Student’s t-test and Chi-square test were used for statistical analysis. Results: CAE was diagnosed in 201 patients (1.59%). The majority (78%) were male. The mean age was 61±10.8 years (range, 25 to 82 years). The cases were divided into 2 groups as isolated CAE (Group 1) (14.9%) and CAE with CAD (Group 2) (85.1%). The risk factors of CAD were similar between two groups. The frequency of arterial involvement was: the right coronary artery (RCA) 54.3%; circumflex artery (Cx), 48.3%; the left anterior descending artery (LAD), 40.4%. CAE affected only one major vessel in 64.2% of cases and all 3 vessels in 9%. Isolated CAE was most commonly detected in Cx (47%). The type of CAE was determined according to Markis and Harikrishnan classification. The most prevalent involvement was Markis type 4 and Harikrishnan type 4a. Although atypical angina was the most common clinical presentation in both groups, acute coronary syndrome was more frequent in Group 2 (p=0.018). Conclusion: The risk factors of CAD and the manner of clinical presentation were considerably similar in both groups and this situation was consistent with similar etiopathogenesis of two diseases.