In the present work, TiO2 films deposited on polyethylene terephthalate substrates by dip coating technique were subsequently treated by DC glow discharge plasma as a function of discharge potential. Hydrophilicity of these TiO2 film surfaces was analyzed by contact angle measurements. Atomic force microscopy (AFM) revealed changes in surface morphology of the plasma treated TiO2 films. Modifications in structural and chemical composition of the TiO2 films were detected by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The blood compatibility of TiO2 films was studied by in vitro investigation which includes thrombus formation and whole blood clotting time analysis (WBCT). It was found that the plasma treatment results in blood compatibility enhancement attributed to the structural, chemical and morphological properties of the modified film surfaces. (C) 2008 Elsevier B.V. All rights reserved.