Despite advances in the processing and display of electroencephalographic (EEG) data, the utility of this inexpensive and noninvasive technique in the investigation of schizophrenia has not been well established. We studied the resting EEG in 19 medication-free patients with chronic schizophrenia and 21 normal controls. Patients with schizophrenia had increased delta activity which was not specific to the frontal regions. Schizophrenic patients also had increased fast activity, and this increase was left sided for the fast beta frequency. Alpha frequency was reduced (less than 10.2 Hz) in 7 of 16 schizophrenic patients. Moreover, those patients with an alpha frequency reduction had a significantly larger mean cerebral ventricular size. These results indicate that the EEG does detect neurophysiological changes in schizophrenia. Our understanding of these changes may be enhanced by other neuroimaging techniques such as computed tomography.