Kinetic resolutions play important roles in industrial biotransformations for production of optical pure compounds from racemic substrates. A simple method, based on enantiomeric excess of both substrate (ee(S)) and the corresponding product (ee(P)), was developed for determination of concentration of enantiomers in kinetic resolution. Since only relative quantity (ee) was required in the proposed method, calibration and cumbersome quantitative sample handling can be avoided and analytical accuracy can be greatly improved.