To comprehend clinical pictures of mitral valve prolapse syndrome (MVP), specific pathoanatomical knowledge is required. There is no definite structure of the anterior mitral valve ring. The mitral valve ring is not flat; the anterior segment of the ring tilts up superiorly. The number of scallops of the posterior leaflet depends on the definition of the incisura. The term "rough zone chorda" (Lam et al., 1970) is a misnomer. From the pathological point of view, more than two subgroups of MVP are present. In isolated MVP, pathological lesions are restricted to the local ballooned segment. However, in MVP with connective tissue disorders (for example, Marfan syndrome, etc.), the lesions are principally diffuse. Mitral valve changes in hypertrophic cardiomyopathy with obstruction are caused by torsion and the relatively elongated anterior leaflet due to narrowing of the mitral orifice, septal hypertrophy and displacement of the papillary muscles. MVP in atrial septal defect is caused by the turbulence of a large shunt flow or by the torsion of the mitral ring due to right ventricular volume overload. Further investigation of surgical and necropsied cases will be required to clearly the subgroups of MVP.