Aim: To evaluate the prevalence and morphological characteristics of coronary artery ectasia (CAE) visualized by 64-MSCT coronary angiography and to determine the clinical presentation, the association of CAE with conventional coronary risk factors and coexisting coronary artery disease (CAD).Methods: This study included 2600 consecutive patients referred to MSCT coronary angiography for a period of 15 months. All patients were subjected to detailed history taking, risk factor assessment, ECG-gated CT angiographic studies were performed to detect and evaluate the coronary artery disease and morphology. Coronary artery ectasia was defined as an arterial segment with a diameter of at least 1.5 times the diameter of the adjacent normal coronary artery. Markis classification was used to clarify the anatomical variation according to the extent of coronary involvement. Results: Coronary artery ectasia was diagnosed in 192 patients, giving prevalence of (7.4%). Most patients were male 169 (88%), mean age 55± 10 years. Hypertension was the most frequent risk factor in 136 cases (70.8%), 38 were diabetic (19.8%), and 61 (31.8%) were smokers. The most common cause for presentation was atypical chest pain (43.8%), then typical chest pain in (31.8%) and for post myocardial infarction risk stratification in (4.7%). The left anterior descending artery was most frequently involved vessel (LAD: 62%, RCA: 56.8%, LCX: 45.8%, LMT: 6.8%). According to Markis classification type I was present in 44 patients (22.9%), type 2 in 34 patients (17.7%), type 3 in 38 patients (19.8%) and type 4 was in 76 patients (39.6%). Ectasia was associated with coexisting atherosclerotic coronary artery disease in 161 patients (84%) with 10 patients (5.2%) had a past history of coronary artery bypass surgery. Conclusion: MSCT coronary angiography is a new non invasive diagnostic tool for detection of CAE. The prevalence of CAE was (7.4%), occurred predominantly in male. The LAD artery was the most affected artery. The distribution of CAE was localized or segmental. Hypertension and smoking were the most prevalent risk factors, with a relatively high prevalence of coexisting coronary artery disease. Absence of diabetes mellitus was noticed in patient with CAE.