A selective and sensitive microemulsion electrokinetic chromatography with laser-induced fluorescence detection method was developed for the quantification of ephedrine (E) and pseudoephedrine (PE) derivatized with 4-chloro-7-nitrobenzo-2-oxa-1, 3-diazol. By a series of optimization, a running buffer composed of 20 mm borate + microemulsion (23.3 mm Sodium dodecyl sulfate/1180.85 mm 1-butanol/16.4 mm n-heptane) +8% acetonitrile was applied for the separation of the derivatives. A linear relationship for E and PE was obtained in the range of 0.058-11.58 mug(.)mL(-1) (correlation coefficient: 0.9993 for E, 0.9995 for PE), and the detection limits for E and PIE were 5.3 and 3.9 ng(.)mL(-1). The method was applied to the analysis of the two alkaloids in Chinese traditional herbal preparations with recoveries in the range of 96.9 +/- 105.4%.