Cardiac myxoma is the most frequent primary tumor of the heart. However, it is rarely associated with congenital cardiac anomalies such as atrial septal defect in the literature. We present a 72-year-old woman referred to the emergency department with loss of consciousness and finally diagnosed as a pedinculated mobile left atrial myxoma and concomitant occurrence of an ostium secundum type atrial septal defect. The mass was successfully excised, and atrial septal defect was safely repaired by primary suture. The patient is currently well after surgery. Atrial myxoma should be considered in the differential diagnosis when patients present with neurological consequences of systemic embolization.