A treatment involving chronic implantation of a receiver that can be activated by an external power source to stimulate specific brain sites has been used in 11 patients with intractable psychiatric illness. All of the patients, a heterogeneous group, had failed to respond to all indicated treatments. Length of illness varied from 6 to 23 years without significant remission. Of the 11 patients, four had uncontrollable violence-aggression (two with no demonstrable organic brain disease and two with brain pathology), five were chronic schizophrenics, and two had lifelong patterns of severe neurosis in addition to the disabling disorder for which the procedure was performed. Three of the 11 patients had seizures in addition to behavioral pathology. Ten of the 11 patients are out of the hospital and functioning without medications or other treatment. Some are symptom-free and others have shown significant improvement. The one patient who failed to respond had an organic lesion over the cerebellar site that was to be stimulated. The rationale for the procedure was based on data gathered during earlier therapeutic studies in patients with depth electrodes and extensive anatomical and physiological experiments in animals. The transistorized stimulator used in treating these patients is similar to stimulators being used for treatment of epileptic and spastic patients.