Two patients with primary cardiac leiomyosarcoma, one of the rarest malignant tumors of the heart, are described. The first patient had a tumor of the pulmonary trunk and was admitted with symptoms suggestive of pulmonary thromboembolism. The second had a tumor of the left atrium and had signs and symptoms of mitral valve obstruction and regurgitation. The 2 patients were operated on and later underwent adjuvant chemotherapy. Both died more than 22 months after operation, having required multiple hospital admissions for treatment of complications related to the pathology or the treatment of the primary cardiac leiomyosarcoma. Nonetheless, aggressive surgical excision followed by chemotherapy appears to have improved survival in these patients with primary cardiac leiomyosarcoma, as they are among the longest survivors reported.