The role of irradiation in the management of synovial sarcoma (SS) in pediatric patients is evaluated. The review covers all children seen at St. Jude Children's Research Hospital between May 1969 and December 1992 with the diagnosis of soft tissue sarcoma, of the 37 patients with the subtype SS, 16 received irradiation for the management of primary site disease. There were four IRS Group I, six Group II, four Group III, and two Group IV patients receiving irradiation. Tumor grade included seven Grade II, and nine Grade III lesions. TMN staging identified eight T1 and eight T2 lesions. Follow-up has ranged from 14 to 117 months (med = 33 months). All IRS Group I patients had documented local control. Five of six IRS Group II and 4/4 Group III patients have had documented local control at last follow-up. IRS Group IV patients had either local control tumor stabilization (n=1) or evidence of tumor regression (n=1) at autopsy. Complications following irradiation include wound dehiscence (n=1), surgery to revise a painful scar (n=1) extremity length discrepancy (n=2), and femoral head avascular necrosis (n=1). At last follow-up, 10 of 14 patients receiving curative intent irradiation remain alive. This review indicates questionable benefit to the addition of irradiation for patients with adequate surgical resection and having "good" tumor characteristics (Grade I, II; IRS Group I, TMN T1A,T1B. For lesions that have had incomplete resection or partial response to chemotherapy, there is evidence that irradiation may provide durable local control. The role of irradiation in those patients with IRS Group IV disease is at present confined to palliative roles until the time when more effective chemotherapy will mandate the decision to treat primary disease for curative measures.