In this work, Reactive Blue 15 dye functionalized poly(HEMA) nanoparticles were synthesized for reversible adsorption of lysozyme from its aqueous solution. For this, nano-sized poly(HEMA) nanoparticles were synthesized by the surfactant free emulsion polymerization. Reactive Blue 15 dye then covalently attached to the polymeric structure. These novel dye attached poly(HEMA) nanoparticles were used for the adsorption of lysozyme. Characterization of dye attached nanoparticles was carried out by using FTIR, AFM, and elemental analysis. Incorporation of the dye onto the polymeric structure was demonstrated by FTIR and elemental analysis, while the size and the shape of the nanoparticles were shown by AFM. The incorporated amount of the dye was found to be 70.3 mu mol/g nanoparticle with sulphur stoichiometry and it was found that the prepared nanoparticles were in a spherical form and were about 100nm diameter. Lysozyme adsorption studies were carried out with different conditions (pH, lysozyme concentration, temperature, and ionic strength) and maximum lysozyme adsorption was found to be 630.7mg/g nanoparticle at pH 7.0 in 25 degrees C medium temperature. Adsorbed lysozyme was desorbed by 1.0M of NaCl with 96% recovery and synthesized dye-attached nanoparticles were used 10 times without any decrease in their adsorption capacity.