Using chitosan as the basis for osteoplastic material, we were dealt with its low biocompatibility. The critical assessment of it is poorly presented in the literature and does not have systematic approaches to solving. The aim of the study was to determine the effect of factors affecting chitosan charge and its free amino groups number on the biocompatibility of hydrogels. Biocompatibility of chitosan compositions were studied in male Wistar rats (n=90). The subcutaneous implantation of chitosan discs and hydrogel caused abundant leukocyte infiltration. The addition of β-glycerophosphate followed by dialysis slightly reduced the inflammatory response. Treatment with a solution of alkali NaOH and NaHCO3 buffer, on the contrary, intensified the inflammatory response. It is confirmed the effect of charged amino groups of chitosan on leukocyte taxis A decrease in the deacetylation degree (DD) of chitosan to 39.0% led to a statistically significant decrease in leukocyte infiltration. Saturation of chitosan hydrogels with PLA granules reduced by 16% the level of leukocyte infiltration, which was supposedly associated with a decrease in the volume of the hydrogel and an increase in the area of its interaction with blood plasma proteins, which reduce the positive charge of chitosan. The most significant reduction in leukocyte infiltration was achieved with a combination of deacetylated to 39.0% chitosan hydrogel with the addition of 16% by weight highly porous PLA granules.