A novel antibacterial coating for cotton fabrics has been developed using core-shell particles that consist of poly(n-butyl acrylate) (PBA) cores and chitosan shells. The spherical particles are prepared via a surfactant-free emulsion copolymerization of n-butyl acrylate in an aqueous chitosan solution induced by a small amount of tert-butyl hydroperoxide. The PBA-chitosan core-shell particles have a narrow particle size distribution with average particle diameter of approximately 300 nm, and display highly positive surface charges. Transmission electron microscopic (TEM) images clearly reveal well-defined core-shell morphology of the particles where PBA cores are coated with chitosan shells. The particle is composed of both the PBA homopolymer and the chitosan-g-PBA copolymer, which have been characterized with FTIR and H-1 NMR spectroscopes. The cotton fabric is coated with PBA-chitosan particles by using a conventional pad-dry-cure method. Its antibacterial efficiency is then evaluated quantitatively against Staphylococcus aureus with the shake flask method. The cotton treated with PBA-chitosan particles demonstrates an excellent antibacterial activity with bacterial reductions more than 99%. (c) 2005 Elsevier Ltd. All rights reserved.