Abstract Congenital left atrial aneurysm is a rare anomaly that has been reported only five times previously. The usual presenting features include an abnormal chest roentgenogram, an apical systolic murmur and supraventricular tachycardia. Even with cineangiocardiography the diagnosis is uncertain, and the lesion is commonly confused with cardiac tumor. Aneurysmectomy is the preferred treatment and has been successful in all patients undergoing operation. The presence of thrombi in the aneurysm necessitates circulatory assistance during excision.