L-Phenylalanine (Phe) was introduced into a porous polyethylene membrane of a hollow-fiber form as a trunk polymer via two schemes using the preirradiation technique of radiation-induced graft polymerization: (1) an epoxy-group-containing vinyl monomer, glycidyl methacrylate (GMA), was grafted onto the membrane before Phe was coupled to the epoxy group, and (2) Phe was initially bound to GMA, and the resultant monomer was grafted onto the membrane. For both resultant membranes, add-on of Phe ligand on the GMA-Phe fiber up to 1.2 mmole per g of the trunk polymer was appended while maintaining 70% of the liquid flux of the original membrane.