Gold nanoparticles are promising materials for biomedical applications because of the attractive optical properties such as the absorption and scattering of light at resonant wavelength. Due to the fruitful applications of gold nanoparticles (GNPs), they are appropriate for a variety of biological studies. One of the most important applications of nanoparticles which consist of transport of therapeutically relevant protein to in vivo or in vitro targets is protein carriers. Protein folding and properties of probable intermediates during the folding of proteins had been investigated in several studies. The molten globule state, a main intermediate of protein folding, has native-like secondary but perturbation of tertiary structure. Consequently, the influence of gold nanoparticles concentration on a model protein was studied at the buffer concentration by far- and near-UV circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), intrinsic fluorescence emission spectroscopy and 8-Anilino-1-naphthalenesulfonic acid binding. The results indicated that the interactions between gold nanoparticles and lysozyme lead to the formation of molten globule-like state.