Epimedii Herba has been used for tonic, cardiotonic, impotency, amnestic and diuretic. Icariin, a main component was isolated from the Epimedii Herba and identified by the spectroscopic methods. In order to evaluate the quality of Epimedii Herba purchased from various regions of Korea, quantitative determination of icariin in Epimedii Herba using HPLC method has been conducted. Quantitative analysis showed the average amount of icariin in commercial 42 samples was 0.34% on the dry weight basis.