Abstract: In B-R buffer solution of pH 3.0,zincon can bind to the proteins form a complex,which results in a remarkably enhancement of the Rayleigh light-scattering(RRLS) signal of zincon.The optimum reaction conditions has been studied in detail,and a new method for the determination of proteins by the resonance Rayleigh light-scattering technique has been developed based on this interaction.The linear range of the method for the determination of bovine serum albumin(BSA),human serum albumin(HSA) and Immunoglobulin G(IgG) are 0.25—12.5 μg/mL,0.10—15.0 μg/mL and 0.10—12.5 μg/mL with a detection limit all below 0.05 μg/mL,respectively.Moreover,a lot of amino acids and metal ions do not interfere in the determination.The method with high sensitivity,good selectivity and reproducibility has been satisfactorily applied to the determination of the total protein in human serum samples.