Zinc-containing hydroxyapatite particles (Zn/HAp) were prepared by an ion exchange reaction process involving hydroxyapatite (HAp) particles with aqueous solutions containing various amounts of zinc nitrate. The Zn2+ ion was partially substituted for the Ca2+ ion position in the HAp lattice, and hence, the obtained samples had changed little in crystallinity, particle size, and specific surface area. Adsorption of bovine serum albumin (BSA) and beta(2)-microglobulin (beta(2)-MG) in solutions containing both BSA and beta(2)-MG was examined. As the Zn2+ ion content in the apatites increased, the adsorbed amount of BSA was almost constant, whereas that of beta(2)-MG increased.