Bone-like hydroxyapatite b-HA formation abilities of b-tricalcium phosphate b-TCP and hydroxyapatite HA after autoclaving were evaluated by immersion tests using simulated body fluid SBF. The b-HA formation was observed on an autoclaved b-TCP, while no deposition was observed on the non-autoclaved one. The b-HA formation on HA was observed to be enhanced after autoclaving. Decrease of surface potentials by autoclaving may enhance the b-HA formation abilities.