There is a continuous search for more efficient treatment of malignant cerebral gliomas. The work of Penn and Croin demonstrates clearly that survival of rats having experimental gliomas is significantly increased by intratumoral chemotherapy. It has been shown that chronic depth electrodes for the investigation of epileptic patients is a reliable and safe method. Using this proven technology originally developed by Talairach, Szikla and co-workers we have developed catheters for intratumoral chemotherapy. Three patients have been treated. It is premature to pretend that this is a treatment which will lengthen the patient's life. Nevertheless, the feasibility of the technique, its precision and safety are assured. Following this course of treatment, we have seen no deteriorations, no side effects, no bone marrow depressions, and no sign of toxicity. Chemical analysis has shown that cisplatin was delivered to the tumor.