Ma huang, the dried plant stem of Ephedra Intermedia Schrenk et CA, is one of the well known medicinal herbs, and has been used for the diaphoretic, antiasthmatic, and diuretic actions. Ma huang is an ephedrine type alkaloid used for the weight loss and energy expenditure. Medications based on the Ma huang have been found to be effective in the treatment of obesity. Neuropeptide Y (NPY), a 36-amino-acid peptide and concentrated in the hypothalamus, stimulates feeding desire and decrease energy expenditure. In the present study, the effect of Ma huang on the expression of NPY in the rat hypothalamus was investigated using immunohistochemistry. The present results demonstrated that Ma huang treatment suppressed weight gain and NPY expression in the hypothalamus depending upon the dosage used. Based on the results, it can be suggested that Ma huang treatment is effective in curbing the desire for food via modulation of NPY expression under the normal conditions.