In post-mortem putamen samples from 27 schizophrenics and 27 controls D2 receptors were measured by Scatchard analysis using 3H-spiperone as a ligand. Maximum number of binding sites (Bmax) and apparent dissociation constant (KD) were significantly increased only in patients in whom neuroleptic medication had been given within a three-month period before death. When the neuroleptic medication had been withdrawn at least 3 month before death, there was a slight, but not significant, reduction in Bmax values and unchanged KD values. Withdrawal of neuroleptic drugs was followed by a normalization of the KD values within 2 weeks and a slower reduction of Bmax values. There were 6 schizophrenic patients with mainly positive schizophrenic symptoms and 17 patients with mainly negative symptoms; positive schizophrenic symptoms were not related to higher Bmax values. There was no difference in 3H-spiperone binding between patients with and without movement disorders (tardive dyskinesia or extrapyramidal symptoms).