Aurantii Fructus has been used in traditional medicine as a digestant, expectorant, and in the treatment of diarrhea, anal prolapse. For the quality control of this crude drug, hesperidin was isolated from the ethylacetate fraction of Citrus aurantium (Rutaceae) and identified by the spectroscopic evidences. A quantitative analysis of hesperidin using HPLC method exhibited that the average contents of hesperidin were $2.13{pm}1.16%$ in 57 samples collected throughout the various regions of Korea.