Dissolving behavior of hydroxyapatite ( HA) ceramics prepared from bovine bone (BHA) was investigated and compared with synthetic HA. BHA power was obtained by calcining at 800 degrees C for 1 h to remove organics and then attritor-milling for 24 h. Synthetic HA and BHA powders were prepared by hot-pressing at 1000 degrees C for 0.5 h under the pressure of 30 MPa in Ar atmosphere. Sintered densities of the synthetic HA and the BHA were about 96% and 95%, respectively. The BHA consisted of mainly HA and small amount of magnesium oxide. Immersion test revealed that there was no clear evidence of dissolution for the BHA, whereas extensive dissolution on the surface of the synthetic HA occurred in buffered water. Accordingly, dense hydroxyapatite from bovine bone was more stable than synthetic HA in liquid environment. (c) 2008 Elsevier B.V. All rights reserved.