Primary or secondary neoplasms can affect the heart. Secondary are more common. However, primary neoplasms are relevant because is a group with diverse genesis, behavior, treatment and clinical manifestations. We present a case of a 45 year-old woman, with recurrent syncope started 1 year before her first consult. She had palpitations and chest pain. Echocardiography identified a left atrium mass of 2.1x1.8 cm. Endomyocardial biopsy document a primary rhabdomyosarcoma of the heart. The patient dies after a overall-survival of 22 months. This case presented had a good study of its symptoms with an accurate diagnosis and early treatment, which provided prolonged survival of this rare and aggressive neoplasm.