Forty-eight patients with primary or metastatic malignant tumors of the central nervous system (CNS) were treated with combination chemotherapy, consisting or procarbazine (100 mg/m2 X 14 days), CCNU (75 mg/m2), and vincristine (1.4 mg/m2 X 2, 1 week apart) (PCV) every 4 weeks. Most patients had undergone initial resection of primary tumors, postoperative radiotherapy, and a post irradiation interval of 3 months or more. Other patients harbored unbiopsied, newly-discovered primary or metastatic tumors. All patients were deteriorating neurologically when treatment began. Overall response rate for PCV combination therapy was 44%, no better than results obtained with single agent procarbazine or BCNU, the most effective drugs used alone in previous brain tumor chemotherapy studies.