We have evaluated the efficacy of intravenous 2,5-diaziridinyl-3,6-biscarboethoxyamino-1,4-benzoquinone (diaziquone or AZQ, NSC-182986) in the treatment of recurrent primary anaplastic brain tumors. Three of 16 evaluable patients (18.8%) showed clinical and radiographic improvement that permitted discontinuation of corticosteroids, 4 patients (25%) showed either clinical or radiographic improvement and were considered partial responders, and 9 patients (56.2%) showed no effects after two courses of AZQ. The treatment was well tolerated, and hematologic toxicity was mild. Pharmacokinetic studies indicated rapid decay of the parent compound from plasma using two different infusion schedules. These results compare favorably with those obtained using the nitrosoureas or procarbazine as single agents.