In a series of 250 cases of cerebral vascular accident, the authors have selected 12 patients whose embolus appeared to have originated in the heart, although this could not be confirmed by clinical examination, ECG, Holter system monitoring and echocardiographic studies. Angiocardiography, complemented or not by His bundle exploration and/or coronary arteriography, revealed the presence of a heart disease likely to produce emboli in 11 cases, and in 8 cases, this was prolapsed mitral valve. These 11 cases represent 4.5% of the whole series and 22% of cases with emboli of suspected cardiac origin. Thorough cardiological studies, therefore, seem to be justified in young adults presenting with stroke. The high incidence of prolapsed mitral valve is in keeping with recently published data.