Intrinsic tissue calcification mainly results from increased penetration of plasma proteins into the leaflets of bioprosthetic cardiac valves. The loss of activity of natural calcification inhibitors changes tissue properties and promotes pathological processes. N-vinylpyrrolidone, 3-amino-1,1-hydroxypropylendiphosphonic acid, O,O-diethylvinylphosphonates and antiaggregant (acryloilsalicylic acid) were used to decrease porosity and prevent calcification. gamma-radiation and glutaraldehyde were used to immobilize these agents. Tissue calcification was studied using subcutaneous implantation of the samples in young rats. The study indicates that the copolymerization of N-vinylpyrrolidone, O,O-diethylvinylphosphonates and acryloilsalicylic acid decreases calcium and phosphorous accumulation during in vivo experiments.