Suitable chromatographic conditions for separation and simultaneous quantitication of emodin and physcion from radix Polygoni cuspidate were developed: column Phenomenex Luna C18 (250 x 4.6 mm; 5 μm); mobile phase is a mixture of methanol - 0.1% phosphoric acid (85: 15), flow rate 1 mL / min; wavelength of detection at 254 nm.