Hydroxyapatite is widely used for bone grafts due to its chemical and structural similarities to the mineral phase of hard tissues and due to its bioactivity and biocompatibility. However, hydroxyapatite has poor mechanical properties due to its brittleness. To improve mechanical properties of hydroxyapatite-ceramics, ceramic oxides, whiskers or fibers have been suggested. In this study, commercial synthetic hydroxyapatite composite reinforced with 5 wt.% Nb2O5 and 5 wt.% MgO was characterized. Microstructural properties of all samples sintered at different temperatures were characterized using scanning electron microscopy technique. Phase analysis was carried out using X-ray diffraction technique. Mechanical properties were measured by compression and hardness tests. The bioactivity property was determined by in vitro bioactivity test. The best obtained values of density, compression strength and Vickers Microhardness were 3.01 g/cm(3), 96 MPa and 393 HV, for composite sintered at 1300 degrees C for 4 hours. Bioactivity results for composite, sintered at 1300 degrees C, show that apatite formation has started after two weeks in a simulated body fluid. At the end of the fourth week, the dense apatite layer and clusters were observed on the surface of the composite.