Coronary artery ectasia (CAE) is a well-recognized angiographic finding, characterized by abnormal dilatation of the coronary arteries. We reviewed the current concepts of the condition including etiology, pathogenesis, flow alterations, clinical implications, prognosis and treatment. CAE is often viewed as a variant of obstructive coronary atherosclerosis. Exaggerated positive vascular remodeling due to inflammation, and chronic overstimulation of the endothelium by nitric oxide are potential causative mechanisms. The condition is associated with cardiovascular risk factors such as smoking and hypertension, while it appears to be inversely associated with age and diabetes mellitus. Patients with CAE typically present with angina, and are at risk for myocardial infarctions and sudden cardiac death due to slow flow, coronary vasospasm, dissection, and/or intracoronary thrombosis. CAE may be a diffuse disease associated with dilatation in other parts of the vasculature. As the incidence of this not so benign condition is expected to rise, the optimal treatment options remain undefined. Medical therapy with anticoagulants, nitrates and calcium channel blockers has been proposed and seems rational; however prospective studies with proof of efficacy are needed.