This paper reports the effects of processing densification on the mechanical properties of hydroxyapatite bioceramics. Densification of synthetic hydroxyapatite is conducted in the range 1000-1300 degrees C. X-ray diffraction and SEM microscopy are used to check the microstructure transformations. Vickers hardness, toughness and Young's modulus are analyzed versus the density and grain size. The sintering temperature and the particle size influence strongly the densification and the resulting mechanical properties. In addition, the critical sintering temperature appears around 1200 degrees C and the declined strength at the temperature up to 1200 degrees C is found sensitive to the dehydroxylation process of hydroxyapatite. (C) 2010 Elsevier Ltd. All rights reserved.