Fibroblast growth factor-2 (FGF-2) was immobilized on a hydroxyapatite (HAP) ceramic in supersaturated calcium phosphate solution prepared using solutions corresponding to clinically approved infusion fluids. To avoid the risk of FGF-2 denaturation, FGF-2 immobilization was carried out at 25 degrees C. FGF-2 was successfully immobilized on HAP ceramic surfaces by deposition with calcium phosphate to form a FGF-2 and calcium phosphate composite layer. A maximum of 2.72 +/- 0.01 mu g cm(-2) of FGF-2 was immobilized in the composite layer formed on the HAP ceramic under the optimum condition. A FGF-2-immobilized HAP ceramic is likely to have the ability to release a sufficient amount of FGF-2 to promote bone formation. FGF-2 released from a FGF-2-immobilized HAP ceramic maintained its biological activity, since the proliferation of fibroblastic NIH3T3 was promoted. Therefore, the FGF-2-immobilized HAP ceramic is expected to be a useful material for promoting new bone formation.