& Aloin, isoaloeresin D, and aloenin-2 0 -p-coumaroyl ester were separated and purified from Aloe barbadensis Mill by one step of high-speed counter-current chromatography for the first time. The separation was performed with an optimized two-phase solvent system composed of hexane-ethyl acetate-acetone-water (0.2:5:1.5:5, v=v=v=v), using the lower phase as the mobile phase in the head-to-tail elution mode. The revolution speed of the separation column, flow rate of the mobile phase, and UV detection wavelength were 860 rpm, 1.5 mL Á min À1 , and 300 nm, respectively. In a one-step operation, 51.9 mg of aloin, 23.1 mg of isoaloeresin D, and 6.5 mg of aloenin-2 0 -p-coumaroyl ester could be obtained from 161.7 mg of dried acetone extract at purities of 99.2%, 98.5%, and 95.6%, respectively, as determined by HPLC using area normalization method. The partial separation of aloin A and aloin B was also obtained. The structures of these compounds were identified by high resolution mass spectroscopy (HRMS), UV, IR, and NMR.