This study is related to the preparation of lysozyme-imprinted poly(hydroxyethyl methacrylate-N-methacryloyl(L)-tyroptophan methylester) [nano-MIP] nanoparticles for purification of lysozyme. Nano-MIP particles were found to be 261 nm in diameter with a surface area of 1648 m(2)/g. According to the elemental analysis results, the particles contained 0.85 mu mol MATrp/g polymer. The maximum lysozyme adsorption capacity was 1182.8 mg/g. Adsorbed lysozyme was desorbed with 94% recovery. It was observed that after five adsorption-desorption cycles there was no significant loss in adsorption capacity. In order to show the selectivity of the Lys-MIP nanoparticles, adsorption of lysozyme, bovine serum albumin (BSA), and cytochrome c were investigated.