The effect of annealing temperature on the characteristics of thin film calcium phosphate coatings fabricated by a novel simultaneous vapor deposition method was investigated. Heat treating the as-deposited films was necessary to change the amorphous coating into a crystalline coating. The films were annealed for 3 h at 400, 700, 1000, and 1200 degreesC in air. After annealing, the structure and the chemical composition of these films were characterized with incident light microscopy, x-ray diffraction. and energy dispersive x-ray spectroscopy. A scratch test was conducted to measure the strength of the adhesion of the coatings to the substrate. The results showed that after annealing at a temperature higher than 700 degreesC, crystalline hydroxyapatite appeared to coexist with tricalcium phosphate and tetracalcium. phosphate phases. A Ca/P ratio close to that of stoichiometric hydroxyapatite was obtained with certain process parameters. The adhesion of the coatings was highly affected by the annealing temperature. From the results, it can be suggested that 1000-1200 degreesC is the best annealing temperature range for calcium phosphate coatings produced by the simultaneous vapor deposition method.