Polyethylene terephthalate polymer is a member of the polyester polymer family that has high mechanical and chemical resistance. The use of artificial vessel prostheses made of polyethylene terephthalate with acceptable physical and biological characteristics is a suitable replacement for damaged vessels. The aim of this study is to investigate the effects of modifying the surface of polyethylene terephthalate with SO2 plasma on the hemocompatibility of the polymer.Polymer films were exposed to SO2 gas plasma. In order to evaluate surface chemistry changes, FTIR infrared spectroscopy test was performed. 3D imaging with atomic force microscope (AFM) was performed to examine the structural changes and MTT assay and platelet adhesion tests were carried out to investigate the changes in cell activity and coagulation.The results of infrared spectroscopy in the sample treated by plasma with SO2gas confirmed the presence of peaks related tothe symmetrical bonds of SO2in SO3 or SO4 in the sample. AFM images showed the surface structure changes. The MTT assay test proved the non-toxicity of the SO2gas plasma surface modification method. Adhesion and cell and platelet activity tests also showed the anti-clotting effect of the modified polymer.The use of plasma method with SO2gas is a suitable method to modify the surface and to increase blood compatibility of polyethylene terephthalate polymer, and probably can be used for making artificial blood vessels. پرونده مقاله