Twenty-three children with CNS tumors were treated with combination chemotherapy including nitrogen mustard, vincristine sulfate, procarbazine, and prednisone (MOPP). All but one had progressive or recurrent tumors following surgery and irradiation. In addition, nine of these patients had prior chemotherapy. Seventeen out of 23 patients (73.4%) responded to MOPP chemotherapy including seven patients who had prior chemotherapy with single or multiple agents such as VCR, nitrosoureas, intrathecal methotrexate, and VM-26. Three comatose patients who were being kept on Decadron without benefit recovered from coma. At the time of this report 8 of the 17 responders are surviving without evidence of recurrence 7--30 months from the start of MOPP chemotherapy. In two of these children chemotherapy has been completely stopped.