One of the most important characteristics that is of great importance for the development of biomaterials based on hyaluronic acid (HA) and its chemically modified derivatives is resistance to hyaluronidases (HA-ase) responsible for the degradation of HA macromolecules. In this work, samples of phosphorylated (HA-P) low and high molecular weight HA (43 kDa and 0.5-0.7 MDa) were obtained by conventional stirring of HA/P2O5 mixtures at different molar ratios (1:0.2, 1: 0.5, 1:1 and 1:2) and exposed to bovine testicular HA-ase (60 or 600 МЕ/mL, [HA]=4 mg/mL of citrate buffer, pH 6.3, 16-18 h). It was found that biodegradability of the HA-P samples obtained at the ratio of 1:0.2, 1: 0.5, and 1:1 was at the level of native HA or even exceeded the HA biodegradability. Only samples obtained at a HA/P2O5 ratio of 1:2 showed resistance to HA-ase: their biodegradability was 13-54% lower compared to that of native HA.