The "association" atrial septal aneurysm and mitral valve prolapse is often asymptomatic with an incidence of about 1% in autopsied adults. Occasionally, however, embolic phenomena can occur. The two-dimensional echocardiography allows an accurate diagnosis of these two cardiac lesions when present. In this paper the Authors report on three patients affected by mitral valve prolapse associated with atrial septal aneurysm, one of whom complicated by a cerebral embolism. Owing to the significant incidence of peripheral or cerebral vascular embolic events in this group of patients, the Authors conclude that long-term anticoagulation therapy is mandatory in all cases, whereas a surgical repair could be advisable when a previous embolism or interatrial shunting is demonstrated.