The measurement of coronary reserve flow by transthoracic echocardiography of the left anterior descending and the posterior interventricular artery is a new non-invasive reproducible and attractive method which can be performed at the bedside with the proviso of a specific learning curve. The potential value is great: detection of significant (> 70%) coronary stenosis, coronary occlusion, post-angioplasty follow-up, evaluation of intermediate stenoses, coupling with stress echo, reperfusion studies, no reflow detection, post-infarction viability, coronary bypass patency and studies of microcirculation.