Neuropeptide-Y (NPY) is the most abundant and widely distributed peptide in the mammalian central nervous system and increases feeding behavior through actions at the Y5 receptor subtype. Recent pharmacological evidence indicates that NPY activity at this receptor subtype can modulate ethanol reinforcement. The purpose of this study was to determine if NPY Y5 receptor antagonism reduces ethanol self-administration and reinforcement in a rodent genetic animal model of alcoholism. Selectively inbred alcohol-preferring (iP) rats were trained to voluntarily consume ethanol (10% vol/vol) versus H2O in a 24-h two-bottle choice test. An additional group of iP rats was trained in operant ethanol self-administration to lever press on a fixed-ratio 1 schedule for ethanol (10% vol/vol) reinforcement. Following establishment of baseline intake or ethanol-reinforced responding, iP rats were injected with L-152,804 (0-20 mg/kg) prior to two-bottle or operant ethanol self-administration sessions. In the two-bottle choice test, L-152,804 (3 and 10 mg/kg, ip) significantly reduced ethanol intake (g/kg) at 4- and 6-h postinjection and had no effect on food intake. In the operant procedure, L-152,804 (10 and 20 mg/kg, ip) significantly reduced both the dosage of self-administered ethanol (g/kg/1-h) and the total number of ethanol-reinforced responses. No effect was observed on latency to the first response or the number of inactive lever presses. These results indicate that blockade of NPY Y5 receptor activity decreases both voluntary ethanol drinking and ethanol reinforcement in a rodent genetic animal model of alcoholism. For this reason, NPY Y5 receptor antagonists may be useful in medical management of alcohol abuse and alcoholism in the human population.