Hydrothermal vapor treatment method was applied for preparation of ceramic biomaterials. Hydroxyapatite (Ca-10(PO4)(6)(OH)(2); HA) ceramics prepared by sintering with random crystal surface have already been used as bone-repairing materials which can directly bond to natural bones. If materials of HA could have the tailored specific crystal surface, they should have the advantage of adsorptive activity and osteoconductivity in comparison with the sintered HA. In the present study, porous HA sheets of about 50 mu m to 1 mm in thickness and porous HA granules of about 50 mu m to 1 mm in size with tailored crystal surface were prepared by the hydrothermal vapor exposure method at temperatures below 200 degrees C. Porous sheets and porous granules of HA with controlled crystal surface should be suitable for scaffold of cultured bone, for bone graft material and for drug delivery system (DDS). (c) 2006 Springer Science + Business Media, Inc.