Tetrahydrogestrinone and related anabolic androgenic steroids (AASs) have been used extensively for performance enhancement (doping) in sports due to their ability to accelerate protein synthesis and improve physical performance (F. C. W. Wu, Clin. Chem., 1997, 43, 1289–1292). The separation of these AASs was performed by micellar electrokinetic chromatography (MEKC) using borate/borax buffer (200/50 mM, pH 8.6), with sodium cholate (40 mM) as a chiral additive. The analytes included two endogenous steroid hormones (testosterone and epitestosterone) and five synthetic anabolic steroids (methyltestosterone, nandrolone, gestrinone, dihydrogestrinone and tetrahydrogestrinone). Capillary electrophoresis parameters such as the concentration of additives, injection time, temperature, and applied voltage were investigated to improve the separation efficiency. A complete separation was achieved in less than 16 min under the optimized conditions. The RSDs of peak area and migration time were below 3.9% and 0.34%, respectively. The limit of detection (LOD) between 240 and 570 ng mL⁻¹ was obtained for each of the pure standards with a photodiode array (PDA) detector. Lower LODs could be reached when combining with preconcentration. After liquid–liquid extraction, the recoveries of spiked urine samples were in the range from 88% to 99%.