Nano-crystalline Zn-containing hydroxyapatite (ZnHAp) was prepared by the wet-chemical method and the selective adsorption of essential proteins was examined, taking bovine serum albumin (BSA) and pathogenic protein such as beta(2)-microglobulin (beta(2)-MG) as model proteins. Transmission electron microscopy observation and X-ray diffraction analysis indicated that the increase of Zn content led to smaller crystallites and their specific surface area of ZnHAps increased with increasing Zn content, accordingly. Furthermore, the amounts of BSA adsorption on ZnHAp particles decreased with increasing Zn content in spite of the increase in the specific surface area. It is thus concluded that nano-crystalline ZnHAps had a highly selective adsorption property with regard to beta(2)-MG.