Polygoni Multiflori Radix, the root of Polygonum multiflorum Thunb., has been used as a tonic, and in the inflammation and constipation in Korea. In order to evaluate the quality of Polygoni Multiflori Radix, the method of isolation and quantitative determination of emodin as a reference standard compound has been developed. Different specimens of Polygoni Multiflori Radix were collected from twenty Korean markets and were analyzed with HPLC using the mobile phase of MeOH-water (64:36). The average content of emodin from Polygoni Multiflori Radix in Korean markets was 0.021%