Primary sarcomas of the CNS are rare and are sometimes associated with chronic subdural effusion (SDE). Approximately 10 patients with such presentations have been reported. The authors report the case of a 5-year-old boy with multiple subdural masses and SDE. An SDE had been diagnosed when the patient was 2 months old, and he received a subduroperitoneal shunt when he was 5 months old. Since then, he had been clinically stable and well for 5 years. When he presented with acute headache, nausea, and vomiting, a newly developed tumor was found. Near-total resection of the tumor was performed, and the mass was diagnosed as an embryonal-type rhabdomyosarcoma. The child was given radiation therapy and 13 cycles of chemotherapy and is still free of disease 13 months after surgery.