Because of the existing relation between myocardial blood flow and systolic function, various noninvasive techniques, capable of assessing regional and global left ventricular function, especially two-dimensional echocardiography, have been used in patients with chest pain, ECG evidence of myocardial ischemia and/or reduced coronary flow reserve and angiographically detected normal coronary vessels. The results, however, have been contradictory, while only few of them have reported stress-induced regional or global left ventricular dysfunction combined with ST-segment depression and/or angina. The reason for such discrepancy could be due to a diffuse but patchy distribution of myocardial ischemia, or to a non-ischemic origin of the clinical and instrumental features of this syndrome, relying on the effect of algogenic mediators, as suggested from recent metabolic studies. Even if the most recent theories agree on the functional involvement of the small coronary vessels, many points on microvascular angina remain confused. An agreement on the nosological classification of this syndrome would be welcome, given the high technological cost required for the study of coronary microcirculation.