PURPOSE: To evaluate the efficacy of combined treatment of surgery and chemoradiotherapy for supratentorial primitive neuroectodermal tumors (SPNET) and obtain the prognostic factors and complications. MATERIAL AND METHODS:The age of 18 patients ranged from 1 to 27 years (median=5 years). There were 12 males and 6 females. The extents of surgery were gross total (n=9), subtotal (n=8), biopsy only (n=1). Craniospinal radiotherapy was delivered to all the patients except 2 patients who were treated only with the whole brain and primary lesion. Radiation dose were 3120-5800cGy (median=5460) to primary mass, 1500-4200cGy (median=3600cGy) to the whole brain and 1320-3600cGy (median= 2400 cGy) to the spinal axis. Chemotherapy was done in 13 patients. Median follow-up period was 45 months ranged from 1 to 89 months. RESULTS: Patterns of failure were as follows; local recurrence (1), multiple intracranial recurrence (2), spinal seeding (3), craniospinal seeding (2) and multiple bone metastasis (1). Two of two patients who did not received craniospinal radiotherapy failed at spinal area. All the relapsed cases died at 1 to 13 months after diagnosis of progression. The 2- and 5-year overall survival rates were 61% and 49%, respectively. The age, sex, tumor location did not influence the survival but aggressive resection with combined chemotherapy showed better outcome. Among 9 survivors, complications were detected as radiation necrosis (n=1), hypopituitarism (n=2), cognitive defect (n=1), memory deficit (n=1), growth retardation (n=1). CONCLUSION: To improve the results of treatment of SPNET, maximal surgical resection followed by radiation therapy and chemotherapy is necessary. The extended radiation field including craniospinal axis may reduce the recurrence in spinal axis.