The authors evaluated the effect of adjuvant therapy (preoperative chemotherapy combined with radiotherapy) followed by radical tumor removal in the treatment of children with primary intracranial yolk sac tumor, embryonal carcinoma, or mixed germ cell tumors containing yolk sac tumor components. Between 1988 and 1995, five consecutive patients were treated with adjuvant therapy followed by total tumor removal. The diagnosis was based on markedly elevated concentrations of serum alpha-fetoprotein (AFP) and/or beta-human chorionic gonadotropin (beta-HCG) in four children and the results of biopsy sampling in one child. The chemotherapy regimen consisted of cisplatin (20 mg/m2) and etoposide (60 mg/m2) daily for 5 days (one course) given three times at 4-weeks intervals. Radiotherapy consisted of 30 to 40 Gy to the whole brain or an area including all ventricles and a 15- to 20-Gy boost to the tumor site. Spinal radiation of 25 Gy was added in one patient. In all patients the serum level of AFP and beta-HCG gradually decreased during the adjuvant therapy and disappeared completely on its completion. In two of the five patients the tumor disappeared as well. In the other three patients the tumor size was moderately or markedly reduced and the remaining tumor was totally removed; there were no neurological deficits. Chemotherapy was maintained after the initial treatment and was repeated every 2 to 4 months for less than 2 years. All children are alive and well without recurrence at 33 to 118 months (average 88 months) after the start of adjuvant therapy. Our preliminary results indicate that adjuvant therapy consisting of combination chemotherapy with cisplatin and etoposide and concomitant radiotherapy, followed by removal of the tumor, is highly effective in the treatment of pediatric patients with primary intracranial yolk sac tumor, embryonal carcinoma, or mixed germ cell tumors containing yolk sac tumor components.