A capillary zone electrophoresis (CZE) method has been developed for simultaneous assay of two bioactive components (p-tyrosol and salidroside) in Rhodiola crenulata and Rhodiola kirilowii for the first time. Those analytes were successfully separated within 15 min using 50 mmol L(-1) (pH 9.62) borate containing 30% methanol as running buffer. Regression equations revealed linear relationships (correlation coefficients 0.9998-0.9999) between peak area and concentration of the two analytes. The relative standard deviations ( RSD) of the migration times and the peak areas of two constituents ranged from 0.51 to 0.57% and from 0.65 to 1.17%, respectively, intra-day, and from 4.91 to 6.93% and from 3.51 to 5.33%, respectively, inter-day. The recoveries of two constituents ranged from 96.24 to 103.15%.