SummaryThe topic of this paper concerns the clinical applications of the M mode echocardiography for the adult patients. The method offers the possibility to diagnose mitral and aortic disease with significant anatomical damage even when the auscultatory signs are lacking. In the cases of cardiomegaly it can differentiate: hypertrophy, dilatation and pericardial effusion.Suspected mitral prolapse and idiopathic hypertrophic subaortic stenosis are easilly confirmed or excluded.The qualitative or semi-quantitative analysis of the mitral echo, the ventricular dimensions, the myocardial thickness and the movements of the septal and posterior walls lead to hemodynamic interpretations. The limitations of the method in this field are briefly discussed.The conclusions outline the clinical situations in wich an echocardiogram is recommanded.