Nanomaterials have small size and unique properties and are used as adsorbents in various fields. For biomaterials, it is necessary to use nanomaterials prepared from nontoxic molecules. Particularly, protein adsorption on hydroxyapatite, Ca-10(PO4)(6)(OH)(2) (HAp), which is highly biocompatible and ecological, was thoroughly studied by varying the reaction conditions and controlling the crystal faces. We easily prepared two peptidecontaining HAp (peptide-HAp) materials with high selectivity for protein adsorption. The morphologies and characteristics of the peptide-HAp composites were similar to those of raw HAp; however, the surface charge was significantly changed by increasing the amount of peptides. The amount of cytochrome c adsorbed on peptideHAp containing poly(L-glutamic acid) and of bovine serum albumin adsorbed on poly(L-lysine)-containing HAp significantly increased compared to that on pure HAp. In addition, as the amount of peptides was increased, peptide-HAp showed improved selectivity for protein adsorption by electrostatic interaction between peptideHAp and protein. Moreover, peptide-HAp could be reused at least five times in adsorption-desorption cycles, and it was expected that the materials could be used as adsorbents and in separation columns.