Polyetherimide (PEI) was carboxylated by activating the PEI backbone with n-butyllithium and subsequent treatment with dry carbon dioxide. This carboxylated form of PEI (CPEI) was then used as the hydrophilic modification agent for the preparation of biocompatible polyacrylonitrile (PAN) hemodialysis membranes. Membranes were prepared with different compositions of PAN and CPEI in the absence and presence of pore former polyethylene glycol-200 (PEG-200) by diffused induced precipitation technique. The prepared membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), differential scanning colorimetery (DSC), scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle, ultrafiltration rate, molecular weight cut off and porosity. Morphological studies revealed that, membranes prepared from pure PAN shows a macrovoidal structure along the entire membrane cross section compared to the spongy structure of the PAN/CPEI blend membranes. Moreover, the hydrophilicity, permeation rate, molecular weight cut off and protein adsorption resistance of the PAN/CPEI blend membranes were found to be improved considerably compared to pure PAN membranes. Platelet adhesion and blood coagulation time upon contact with these membranes were studied and it revealed that both are intricately linked to surface wettability and protein adsorption resistance. The efficiency of these membranes in the removal of uremic toxins such as urea, creatinine and cyctochrome C was studied by a single membrane dialysis system and significant improvement was observed for PAN/CPEI blend membranes. Thus the overall results illustrated that biocompatible PAN/CPEI blend membranes with optimum separation efficiency will be valuable for blood purification therapy of hemodialysis patients. (C) 2013 Elsevier B.V. All rights reserved.