Primary osteosarcoma of the heart is an extremely rare entity. In this report, we describe a case of primary osteosarcoma of the heart that recurred and metastasized. The patient is a 50-year-old woman who presented with an abrupt onset of dyspnea, dizziness, and palpitations. Echocardiography results showed a left atrial tumor that was resected and had histological features of high-grade osteosarcoma. The patient was treated with adjuvant chemotherapy. The tumor recurred in the same location 4 years later and was resected. Three years later, the patient presented with a 4-cm polypoid mass in the stomach that was consistent with metastatic osteosarcoma. One year later, the patient presented with recurrent high-grade sarcoma in the soft tissue of the left chest wall. We herein present the spectrum of histological findings and molecular genotyping data.