Inosine peripherally administered to rats markedly suppressed spontaneous food intake and food intake induced by diazepam, muscimol, insulin, and food deprivation. The purines 2-deoxyguanosine and 2-deoxyinosine also suppressed food deprivation-induced feeding, whereas 7-methylinosine, which does not bind to the benzodiazepine binding site in vitro, had no effect on food intake when compared with controls. These results suggest that purines may represent endogenous substances that regulate food intake through interactions with the benzodiazepine receptor.