Rats were implanted with osmotic minipumps SC that infused either saline or 10 mg/kg/day phencyclidine (PCP) for 10 days, a regimen that produces dependence to PCP. At the end of this 10-day infusion period, the pumps were removed and the rats were sacrificed either immediately or at various time points (12 h, 1, 2, and 7 days) after pump removal. The saturation binding parameters of [3H]MK-801 were then determined in well-washed cortical/hippocampal membranes prepared from these rats. Neither the Bmax nor the Kd of [3H]MK-801 binding in membranes of PCP-treated rats differed from that determined using membranes from saline-treated rats at any time point studied. These results suggest that alterations in PCP receptors do not play a major role in the production of PCP dependence.