Costello syndrome, a rare entity with multiple congenital anomalies, has been associated with a high incidence of benign and malignant tumors, particularly rhabdomyosarcoma. Although the head and neck is the most common site for rhabdomyosarcomas in children, only one other case in the literature has been reported of a head and neck rhabdomyosarcoma in a Costello patient. The authors describe a 3-year-old with a parameningeal infratemporal fossa rhabdomyosarcoma. Management is discussed with particular attention to the difficulties encountered due to the congenital heart abnormalities associated with the syndrome.