Patients with chronic schizophrenia were examined by nuclear magnetic resonance imaging of the brain. Subgroups of the syndrome with high positive or high negative symptom scores and ventricular dilatation were compared with each other and with normal controls in respect of regional spin lattice relaxation time (T1) changes. Significant differences were not observed between the schizophrenic subgroups and controls but there were significant differences between the subgroups themselves. The presence of tardive dyskinesia was associated with increased T1 of the basal ganglia. The significance of these results is discussed in relation to findings using other techniques.