The objects of investigation were the amorphous copolymers: №1 - styrol (ST) + butyl methacrylate (MBA) + methacrylic acid (MA) in composition (40:50:10) mole %, №2 – the copolymer with the same composition but changed by grafting the ampicillin to COOH groups]. The scheme of copolymer synthesis is presented on Scheme 1. Scheme 1. The scheme of synthesis of copolymer styrol (ST) + butyl methacrylate (MBA) + methacrylic acid (MA). Grafting of ampicillin to copolymer was carried out following the scheme using ethyl chloroformate In this wor microhardness (H) was studied. Method in large interval of loads (P) and temperatures (T) was applied. The H(P) dependence represents the clear two-steps form. Microhardness is increased with increasing the load on indenter. However, velocity of microhardness change by deformation forces is determined. Analogous course of dependence is observed for layers of thickness in region of ~10- 22 μm. The character of H(P) dependence with indentation time increase did practically not change: form of H change with P increase is saved. As a creep characteristics the time dependence of d2 parameter (d- imprint diagonal) d2(t) was used . Estimation of strain-hardening coefficient θ=ΔH/ΔP for each stage was performed. Influence of temperature on H magnitude was carried out with a view of assess the glass transition temperature Tg (Tsoftening) for polymers studied. Microhardness modifications in the temperature interval of the 40 – 750C were investigated. Temperature of vitrification (softening) Tg as temperature of middle interval was estimated and in our case for polymers №1 Tg=57oC. Value of microhardness in that temperature interval was varied from 7 to 13 kg/mm2,. The microindentation process and material sealing are possible connected with the free volume concept. The compression of polymer due to the high pressures with closure of fluctuated microvoids is rather connected So, it was established : 1.Microhardness of copolymers №1 and №2 is increased with the deformation effort under microindentation increase. It was proposed the explanation to mechanical properties of polymers revealed. The last effect is possible connected with behavior of microvoids, 2.It was indicated, that.iIntroduction of addition into copolymer №1 at little loads (P< 0,05N) results in the forming of copolymer with more harden structure. Possible, in the result of ampicillin graft to COOH copolymer group the space lattice (conformation) of copolymer №1 becomes modified that promotes to the forming of polymer №2 with others mechanical properties.