The aim of this study was to synthesize yttrium/hydroxyapatite(Y/HA) nanoparticles and submit to a structural, chemical and biological characterization. The microstructure, shape and size, concentration of yttrium released in water were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and Inductively coupled plasma (ICP). The biological actions were evaluated by the cell cultivation method and oral bacterial colony counting method. The results showed that yttrium can be incorporated into the hydroxyapatite structure. Sizes of the nanocrystals were less than 100nm. The shape was needle-like. The human periodontal fibroblast growth was accelerated and oral bacterial growth was lightly restricted. The data indicate that the hydrothermally synthetized approach can be successfully used to prepare yttrium/hydroxyapatite nanocrystals with crystallinity, crystal dimensions, structure and stability close to those characteristic of biological apatite and with better biological activity, bacteriostasis.