Coronary flow reserve is the capacity of the coronary circulation to augment the blood flow in response an increase in myocardial metabolic demands and has a powerful prognostic significance in different clinical situations. It might assess with invasive and non-invasive technique. Transthoracic echocardiography Doppler is an emerging diagnostic technique, noninvasive, highly feasible, safe for patient and physician, without radiation, able to detect macrovascular and microvascular anomalies in the coronary circulation. This review aims to describe the benefit and limits of noninvasive assessment of coronary flow reserve, in particular his evaluation with echocardiography.