The PCP analog metaphit, a proposed PCP receptor acylator, produced a concentration-dependent loss of the number of high-affinity [3H]cocaine binding sites in rodent striatum. In addition, 24 h after administration of metaphit, a dose of 25 mg/kg of cocaine was not effective in stimulating locomotor behavior of rodents. The results suggest that metaphit antagonizes cocaine-induced locomotor stimulation by acylating cocaine binding sites on dopaminergic nerve terminals.