The purpose of this research was to examine changes in the ratio and amplitude of the N40 component of the auditory event-related potential (ERP) in the paired conditioning (C) test (T) stimulation paradigm following subchronic cocaine/vehicle administration. Free moving rats received cocaine (47.5 mg/ kg) or saline for 7 consecutive days in a longitudinal crossover design. ERPs were recorded 4 and 7 days after each treatment and again 4 and 7 days following withdrawal of the drug/vehicle. Cocaine led to a progressive increase in the T/C ratio indicating impaired inhibition of the test response. This trend continued throughout the 7-day drug regimen. Following withdrawal of the drug the T/C ratio gradually normalized over the next 7 days but remained elevated at 4 days postdrug. A significant increase in the test response accompanied by a less pronounced decrease in the conditioning response accounted for the observed results. Behavioral state as measured on a rating scale during ERP sampling did not differ across experimental conditions.