Primary cardiac tumors are infrequent, less than 15-20% are malignant, and most of them are sarcomas. Primary recidivant cardiac osteosarcomas are extremely rare, only a few cases have been reported, and the prognosis is ominous. We report a case of a primary cardiac osteosarcoma in a 70-year-old woman who was admitted to the hospital for evaluation of congestive heart failure. Despite the wide resection of the tumor, a local and metastatic recurrence was diagnosed. In this report, we illustrate the utility of image techniques for the diagnosis and the monitoring of primary cardiac tumors, especially the role of bone scintigraphy. This technique is not a routine procedure for the cardiologist, but it has been very useful in this case in order to decide the optimal treatment.