Radical grafting of biocidal precursor monomer 3-allyl-5,5-dimethylhydantoin (ADMH) onto poly(ethylene terephthalate) (PET) fabric was investigated. Based on SEM pictures, it was suggested that benzoyl peroxide could generate macromolecular radicals on PET when it was delivered to the areas properly. The macroradicals were in a form of benzoyl structure which can react with ADMH to form a short chain graft. It seems the reaction occurred at the end of polymers or defect areas with terephthalate groups at the end. After being converted to N-chloramide structure, the poly(ADMH)-g-PET fabric demonstrates total kill of 10(5)-10(6) CFU/mL Eschenichia coli at a contact time of 2 h. (c) 2008 Elsevier Ltd. All rights reserved.