Although the activity of antipsychotic agents is generally associated with their influence on dopaminergic neurons, their structural relationship to the neurotransmitter dopamine is not readily apparent. In this communication, we describe a novel class of dopamine receptor antagonists and neuroleptics, 2,3,4,5-tetrahydro-7,8-dihydroxy-6-(phenylthio)-1H-3-benzazepines (e.g., 1, SK&F 83742), which clearly incorporate the structure of dopamine within their molecular framework. These agents were identified from an extensive study of relatives of 2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine (2, SK&F 38393), a potent agonist of both central and peripheral dopamine receptors. The 6-(phenylthio)-substituted benzazepines were synthesized by oxidizing the corresponding dimethoxybenzazepine derivatives (obtained via reflux of dimethoxybenzazepines in 48% HBr) with DDQ to form dione hydrobromide salts, followed by reaction with thiophenol. Their dopamine receptor antagonist activity was evaluated by inhibiting dopamine-sensitive adenylate cyclase in rat striatal tissue, while neuroleptic activity was assessed through tests of avoidance acquisition blockade and catalepsy induction in rats. Compound 1 showed selective peripheral dopamine receptor antagonist activity: it dose-dependently antagonized dopamine-induced renal vasodilation without affecting bradykinin-mediated renal vascular responses. The results indicate that structural modifications of 2 can separate its partial agonism, yielding potent and selective dopamine receptor agonists and antagonists that retain the catecholamine moiety of the natural agonist dopamine.