Thirty-six previously untreated patients younger than 21 years of age with sarcoma arising in the perineal region were entered on the Intergroup Rhabdomyosarcoma Studies (IRS) I and II from 1972 through 1984. The tumor histologic subtype was alveolar rhabdomyosarcoma (RMS) in 20 patients (56%), embryonal RMS in 11 patients (30%), and other types of sarcoma in 5 patients (14%). Fifteen children had grossly complete surgical excision (Clinical Groups I and II), and 15 had localized gross residual tumor (Group III) after initial operative management. Six patients had distant metastases (Group IV) at diagnosis. Twelve patients without distant metastases underwent regional lymph node biopsy; tumor involvement was found in six. Subsequent treatment consisted of chemotherapy with vincristine (VCR) and dactinomycin (AMD) for all patients; patients in Groups III and IV also received cyclophosphamide (CYC) with or without Adriamycin (ADR) (doxorubicin; Adria Laboratories, Columbus, OH). Radiation therapy (RT) was administered to patients in Clinical Groups II, III, and IV. Overall, 28 (78%) patients achieved a complete clinical response. The 3-year disease-free survival rate for these patients was 42%, compared with 52% for all other patients in the combined IRS I and IRS II series (P = 0.44). The overall 3-year survival rate was 59%, compared with 64% for all other patients in IRS I and IRS II (P = 0.48). Aggressive treatment is needed in children with perineal sarcoma to improve their prognosis.