Bioactive glasses and glass-ceramics can be applied as fillers of bone defects due to their stimulating effect on the regeneration of the bone tissue. Four kinds of such materials of CaO-P2O5-SiO2 system with the symbols: RM, RMC, S2 and A2 have been obtained in laboratory conditions. The RM and RMC materials were produced by the melting method, and the S2 and A2 materials-by the chemical sol-gel method. The final products had the form of granules 100-800 um. The materials were characterised with respect to surface development and behaviour in simulated body fluid SBF. It has been found that in SBF the materials become covered with a surface hydroxyapatite layer, which is evidence of their bioactive properties. In order to estimate the biocompatibility of the obtained materials they have been subjected to selected tests in vivo. The granules were implanted in the skeleton muscle of rats in order to determine the progress of regeneration and the degree of tissue biocompatibility. Intensive phagocytosis of the material particles in the case of gel-derived A2 and S2 implants was observed. The melted materials RM and RMC showed low level of phagocytosis by macrophages, however these materials were surrounded by the so-called cells around the alien body. Certain reduction of metabolism was observed in the muscle fibres situated near the RM and RMC biomaterials, whereas near the A2 implants-good, progressive regeneration of the muscle fibres was observed. Attempts have been made to explain the observed, differentiated biological phenomena stimulated by biomaterials, using the supplementary immuno-histolochemical tests.