Cotton fabric with excellent antibacterial durability was obtained when treated with chitosan-containing core-shell particles without any chemical binders. These amphiphilic nanosized particles with antibacterial chitosan shells covalently grafted onto polymer cores were prepared via a surfactant-free emulsion copolymerization in aqueous chitosan. Herein, two core-shell particles, one with poly (n-butyl acrylate) soft core and another with crosslinked poly(N-isopropylamide) hard core, were synthesized and applied to cotton fabric by a conventional pad-dry-cure process. Antimicrobial activity was evaluated quantitatively using a Shake Flask Method in which the reduction of the number of Staphylococcus aureus cells was counted. The results showed that treated fabric had an excellent antibacterial property with bacterial reduction higher than 99%. The antibacterial activity maintained at over 90% reduction level even after 50 times of home laundering. The fabric surface morphology as well as the effect of latex particles with different core flexibilities on fabric hand, air permeability, break tensile strength, and elongation was investigated. (c) 2006 Wiley Periodicals, Inc.