Abstract 1. 1. In vitro receptor autoradiography was used to examine the long-term effects of a typical (fluphenazine), atypical (clozapine), or potential atypical antipsychotic (S[+]-N- n-propylnorapomorphine; [+]-NPA) on different dopamine (DA) receptor subtypes. 2. 2. D 1-Like and D 3 receptor levels were not changed with any treatment in any brain region examined. 3. 3. D 2 Receptors in caudate-putamen (CPu), nucleus accumbens (NAc) and olfactory tubercle (OT) were significantly increased by long-term treatment with fluphenazine, but not with clozapine or S[+]-NPA. 4. 4. D 2 Receptor levels in medial prefrontal cortex (MPC), but not dorsolateral frontal cortex (DFC), were elevated after repeated daily administration of fluphenazine, clozapine, and S[+]-NPA. 5. 5. D 4-Like receptors, assayed under D 4-selective conditions, were increased by fluphenazine, clozapine and S(+)-NPA in both NAc and CPu, but by none of these treatments in OT, DFC or MPC. 6. 6. These results support a common role for medial prefrontal cortical D 2 and striatolimbic D 4 receptors in mediating the clinical actions of typical and atypical antipsychotic drugs.