Four different bioreactive ceramics were prepared using a sol-gel method and a standard melting process. The aim was to study antibacterial effect of these materials on the growth of Staphylococcus epidermidis. The dissolution (Si and Ca ions) of fine (≤ 45 !m) ceramic powders in a tryptone soya broth (TSB) was investigated. Also the pH changes in TSB solution were measured. In addition the adherence of Enterococcus faecalis (Ef) to materials was investigated. The bacterial adhesion was studied using scanning electron microscopy (SEM). In the bacterial and the adhesion test, CaPSiO2 and S53P4 had the strongest antimicrobial effect against studied bacteria. It was shown that bioreactive sol-gel derived ceramic with sufficient high Ca ion release (> 270 ppm) can reach strong antibacterial effect also at lower pH values (< 9.6).