Congenital sinus of Valsalva (SOV) aneurysm is a rare cardiac abnormality. Rarely the aneurysm enlarges without rupture, cause symptoms of the mass effect by compressing the adjacent structures, obstruction of the right ventricular outflow with tricuspid regurgitation, infectious endocarditis, thrombus formation and myocardial ischemia/infarction. And SOV aneurysm can also be a source of embolism. We observed a patient with cerebral infarction in whom a huge SOV aneurysm, was diagnosed as the presumed source of cerebral embolism and the cause of hypoplastic tricuspid valve.