Hunger drives animals to search for food, a behavior that is heavily dependent on the olfactory system. The neuronal mechanism by which hunger modulates the behavioral response towards food odor, however, is not well understood. In this study, using a single-fly behavioral assay and single-unit recording, we have demonstrated that starved flies exhibit enhanced attraction towards an attractive odor, ethyl acetate, via increased sensitization of the olfactory receptor neurons (ORNs). These results suggest that the increased attraction behavior caused by hunger is due to enhanced sensitivity in the ORNs.