Abstract: A pepsin modified poly(glycidyl methacrylate-ethyleneglycol dimethacrylate)(poly(GMA-EDMA))capillary monolith(32 cm×75 μm, effective lenth 22 cm)was applied in exploring the interaction between nefopam enantiomers and bovine serum albumin(BSA). Frontal analysis was used to measure the binding constant, number of binding sites and the location of binding sites of BSA to both nefopam enantiomers. Optimal CEC conditions were as follows: 15 mmol/L ammonium acetate was adjusted to pH 5. 5 as running buffer, separation voltage was 5. 0 kV, detection wavelength was 215 nm, and samples were dissolved with 50 mmol/L ammonium acetate buffer at pH 7. 4 and were injected at 10 kV×6 s. The results indicated that two enantiomers could successfully separated by CEC on the monolith column. BSA in the binding system showed no effect on the separation and determination of nefopam enantiomers. Frontal analysis demonstrated that BSA has only one binding site with both enantiomers, with binding constants(K)of 443 L/mol and 527 L/mol, respectively. The displacement expe-riments indicated that binding site of both isomers to BSA molecule was Sudlow siteⅡ.