Abstract. The aim of current study is the determination of content of bound protein in conjugated vaccines  by applying UV – spectrophotometry. The obtained regression equation: y = 8623.x + 0.0507, shows the proportional accordance А = f (C) in linear concentration range: 1.10^–5 µg/ml ÷ 9.10^–5 μg/ml. Accuracy is presented by the degree recovery R (%) ± RSD (%), which for results suit relevant confidence interval: 94.09 % ¸ 102.91 % (С_P17); 98.91 % ¸ 103.1 % (С_P40.5); 99.14 % ¸ 100.30 % (С_P64). Precision (repeatability) is determined by: SD, RSD and confidential interval. All  results for the obtained content of protein in model mixtures correspond to the relevant confidence interval: 15.13 ¸ 17.65 (С_P17); 39.54 ¸ 42.28 (С_P40.5), 63.12 ¸ 64.52 (С_P64).  The obtained quantity protein in vaccine is (29.23 µg ¸ 36.51 µg)/0.5 ml and suit to the higher labeled content: (27.2 µg ¸ 36.8 µg)/0.5 ml.