A novel cyclic-amine monomer, 3-allyl-5,5-dimethylhydantoin (ADMH) was synthesized and characterized. ADMH alone could not be grafted onto ordinary polymers. However, the presence of triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TATAT) remarkably enhanced the ADMH grafting yield onto synthetic fabrics. The influences of reaction conditions on the grafting copolymerization were investigated. After chlorine bleach treatment, hydantoin units in the grafted copolymers were transformed into N-halamine structures. Treated samples exhibited potent antibacterial activity against Escherichia coli, and the functional properties were shown to be durable and regenerable.