The Institute for Nuclear Problems of the Belarusian State University (INP BSU) has developed equipment and optimized the technology for synthesizing boron-doped pyrocarbon, a material for application in heart valve endoprostheses.The purpose of this work was to evaluate the general and biochemical blood tests, mass coefficients of animal organs and the dynamics of reactions of rat tissues to implantation of pyrocarbon material in the subcutaneous tissues of the interscapular region. Animals were monitored for 90 days. According to the morphometric data, the boron-doped pyrocarbon, synthesized in INP BSU, was found to be non-irritating to the tissue in comparison with the control sample during all periods of observation. There was no significant effect of implantation of pyrolytic carbon on the parameters of the blood general and biochemical analysis in rats compared with healthy animals. The results of necropsy showed that the mass of organs and mass coefficients of animals did not deviate from the physiological norm during different periods of pyrocarbon sample implantation.Thus, the boron-doped pyrocarbon material synthesized in INP BSU can be used for manufacturing heart valve endoprostheses.