Zwitterionic hyperbranched polyester (HBPE) synthesized on bare metal stents (BMS) surface by surfaceinitiated atom transfer radical polymerization (SI-ATRP) method. The modified BMS obtained was tested for its blood compatibility. The blood compatibility studies were including, platelet adhesion tests, hemolysis assay, morphological changes in RBCs, coagulation tests, PRT assay, complement activation, platelet activation, and the cytotoxicity was also investigated. The modified BMS surface does not cause platelets adherent, red blood cell disruption, hemolysis and does not induce complement and platelets activation. All results indicated that the modified BMS was blood compatible and no cytotoxicity. It has the potential use for biomedical applications. (C) 2014 Elsevier Inc. All rights reserved.