The aim of this study is to investigate in detail the feasibility of poly(2-hydroxyethyl methacrylate-N-methacryloyl-(L)-histidine methyl ester), PHEMAH membranes for purification of immunoglobulin G (IgG) from human plasma. PHEMAH membranes were prepared by photo-polymerization technique. Then, Zn2+, Ni2+, Co2+, and Cu2+ ions were chelated directly on the PHEMAH membranes. Elemental analysis assay was performed to determine the nitrogen content and polymerized MAH was calculated as 168.5 mu mol/g. The nonspecific IgG adsorption onto the plain PHEMA membranes was negligible (about 0.25 mg/mL). A remarkable increase in the IgG adsorption capacities were achieved from human plasma with PHEMAH membranes (up to 68.4 mg/mL). Further increase was observed with the metal-chelated PHEMAH membranes (up to 118 mg/mL). The metal-chelate affinity membranes allowed the one-step separation of IgG from human plasma. The binding range of metal ions for surface histidines from human plasma followed the order: Cu2+ > Ni2+ > Zn2+ > Co2+. Adsorbed IgG was eluted using 250 mM EDTA with a purity of 94.1%. IgG molecules could be repeatedly adsorbed and eluted with the metal-chelated PHEMAH membranes without noticeable loss in their IgG adsorption capacity. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 3476-3484, 2012