We report the occurrence of a clinically undiagnosed biatrial myxoma with left ventricular involvement in a 2-month-old male infant, resulting in sudden death. During a routine well-baby examination, a grade (34) holosystolic murmur was detected at the left sternal border with radiation to the axilla and back. On the following day, the patient collapsed and died suddenly. An autopsy revealed a large multifocal neoplasm diffusely involving the aortic valve while displaying mitral, tricuspid, and left ventricular extensions. The ensuing histopathologic and immunohistochemical studies were diagnostic for myxoma. We discuss the occurrence of cardiac myxoma within the pediatric population and review the literature as to theorize whether this lesion was a congenital process versus a rapidly growing tumor that developed after the child was born. Lastly, we address the potential for sudden death in patients with such tumors.