The comparative study of the antioxidant activity of whey protein concentrate, native colostrum, their ultrafiltered hydrolysates, as well as complexes of ultrafiltered hydrolysates with Y-cyclodextrin was carried out. The dependences of the fluorescence intensity of fluorescein on the logarithm of the concentration of all samples were obtained, from which the IC50 values were graphically determined, which were in the range of 7,2-103,4 gg/ml. Complexes of ultrafiltrate hydrolysates with Y-cyclodextrin restored fluorescein fluorescence to 88-96 % at a sample concentration of 0,68-0,75 mg/ml.