Although it is recognized that aggressive soft tissue sarcomas may give rise to cardiac metastases, these manifestations are usually late and clinically silent, being the prevailing finding in exceptional cases. This report describes the occurrence of a massive cardiac metastasis at diagnosis of leg rhabdomyosarcoma in a middle-age adult. This manifestation was the cause of rapidly progressive congestive heart failure and, together with the unusual occurrence of autoimmune thrombocytopenia, led to difficult patient care with a significantly negative influence on the outcome.