Although hematological malignancies are a known complication of Down syndrome, few reports have described cases involving solid tumors. We describe the case of a 3-year-old Down syndrome girl with a primary solid cardiac tumor. Outpatient echocardiography after intracardiac repair of a ventricular septal defect at 6 months of age revealed a highly mobile pedunculated mass (8 × 9 mm) on the free wall of the right atrium. Due to potential incarceration of the mass in the tricuspid orifice, it was excised under extracorporeal circulation and cardiac arrest. Macroscopically, the tumor closely resembled a papillary fibroelastoma, although histopathological tests were inconclusive.