The assessment of coronary flow reserve by transthoracic echocardiography has recently been introduced into clinical practice with good results for the diagnosis of left anterior descending artery disease and fairly promising results for posterior descending coronary artery disease. By looking at what is behind wall motion, we may realize a sonographer's dream and, in particular, the addition of coronary flow reserve to regional wall motion analysis allows us to have - in the same sitting - high specificity (regional wall motion) and a highly sensitive (coronary flow reserve) diagnostic marker, with an improvement in overall diagnostic accuracy. Coronary flow reserve evaluation may shift the balance of stress choice in favor of vasodilators, which are easier to perform with dual imaging than dobutamine or exercise coronary flow reserve evaluation and may shift the choice in favor of dipyridamole or adenosine stress tests, which are also easier to perform with dual imaging than those using dobutamine or exercise. Lastly, it adds quantitative support to the exquisitely qualitative assessment of wall motion analysis, thereby facilitating the communication of stress echo results to the cardiological world outside the echo laboratory.