In this work, in order to enhance the grafting degree, N-vinyl pyrrolidone (NVP) was used to assist the melt grafting of the macromonomer-poly(ethylene glycol) methyl ether methacrylate (PEGM)-which has good hemocompatible property, onto styrene-b-(ethylene-co-butylene)-b-styrene (SEBS) elastomer with free radical initiator. The grafting degree of PEGM with NVP assistance was increased by at least 4-fold to those without NW. In addition, side reactions such as homopolyerization of the PEGM monomer during the melt grafting process could be largely reduced in the NVP-assisted system. Both the hydrophilicity and hemocompatibility of the PEGM modified SEBS were highly improved. Comparing to virgin SEBS, the amount of fibrinogen adsorption was reduced by up to 75% in the NW-assisted grafting samples. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.