High molecular weight compounds find wide application at the present time in modern medicine as raw materials for the preparation of instruments, sanitation articles, materials for stomatology, medicaments, blood substitutes, and for producing artificial organs [4, 9]. Prostheses of the latter present the science with several problems, the most important being the investigation of the reaction of polymers with tissues and blood of the organism. One of the principal requirements of polymers for medical purposes is their antithrombogenic character, and therefore production of polymers, which do not cause the production of thrombi is a current problem. We studied the influence of a "Diflon" polycarbonate, poly(butylene terephthalate), poly(4-methylpentene), polyfluoroethylene resin, a TPU-3BT polyurethane, and polyethylene on the hemocoagulation process, the electrophoretic mobility of erythrocytes and thromboeytes and the resistance of erythrocytes in hydrochloric acid. The results of biochemical investigations are given for connective tissue capsules developing around polymeric materials made of a PPE-201 polyurethane and polyethylene, in order to study the biocompatibility of tissues and blood of animals with the above polymers.