Application of a new hydroxyapatite coating method called the laser-assisted laser ablation method improves adhesion due to irradiation by an assist laser beam for optical annealing. In this study, substrate immersion in a simulated body fluid was performed to confirm the biocompatibility of the technique. The coatings contained a significant quantity of amorphous calcium phosphates. The amorphous phase was dissolved in the simulated body fluid, but coatings in the assisted area remained and grew in the solution. It is shown that the assist laser annealed the coatings and micro-crystals of hydroxyapatite were achieved. (C) 2002 Elsevier Science B.V. All rights reserved.