Seventy-five children with recurrent, progressive or metastatic primary brain tumors were treated with aziridinylbenzoquinone (AZQ; Diaziquone) at 9 mg/m2/day by 30-minute intravenous infusion for five days every three weeks. Sixty-six patients were evaluable for response by imaging studies. There were five partial responses and one complete response for a combined response rate of 9%. A complete response lasting for 35+ months occurred in one of twelve patients with metastatic or locally recurrent ependymoma. Objective responses were also seen in patients with primitive neuroectodermal tumors (PNET) (1/8), low-grade glioma (1/6), and primary central nervous system lymphoma (1/1). Stable disease of greater than six months duration was seen in patients with ependymoma, PNET and medulloblastoma. Profound and prolonged myelo-suppression was the significant toxicity observed. As administered in this study, AZQ has marginal activity and severe toxicity.