Polyethersulfone (PES) membranes with improved hemocompatibility were prepared via solid-liquid interface aminolysis and heparinization. Reactive amino groups were generated by immersing solid PES membranes in proper diamine solution. Heparin was covalent immobilized on the surface via amide bond. The feasibility of surface aminolysis for the introduction of amino groups and the effectiveness for further heparin immobilization were confirmed by surface group analysis. The effect of aminolysis time on surface amino group concentration and bulk mechanical properties was investigated. The surface amino group concentration determined the amount and bioactivity of immobilized heparin chains. SEM images suggested that both the aminolysis and heparinization reaction had little effect on the surface morphology of PES membranes. Contact angle measurement, surface charge analysis, protein and platelet adsorption/adhesion experiment were applied to study the surface properties. The results showed that the heparinized PES membranes displayed enhanced hydrophilicity and hernocompatibility, indicating potential application in blood purification and other blood contacting fields. (c) 2014 Elsevier Inc. All rights reserved.