Ma huang, the dried plant stem of ephedra intermedia Schrenk et C.A., contains an ephedrine-type alkaloid and has been used for weight loss. Neuropeptide Y (NPY), a 36-amino acid peptide, is concentrated in the hypothalamus and stimulates feeding desire. In this study, the effect of ma huang on the expressions of NPY in the hypothalamus of rats was investigated using immunohistochemistry. Food-deprivation enhanced the NPY expression in the hypothalamus. ma huang suppressed the food-deprivation-induced enhancement of NPY expression. Present results suggest that ma huang curbs the food desire by suppressing the NPY expression under food-deprivation conditions.