An 18-month-old boy presented with signs of increased intracranial pressure. Computed tomographic scans of the brain and lungs showed multiple masses in the brain and lungs. Echocardiography revealed homogeneous, irregular pericardial thickening, minimal pericardial effusion, and irregular echogenic areas in the left ventricular inferoposterior and apical regions. Postmortem examination of tumor tissue showed that the masses were primary rhabdomyosarcoma of the left ventricle with multiple metastases. Primary rhabdomyosarcoma of the heart is uncommon, especially in patients under 2 years of age.