The present invention describes a novel antibacterial treatment on textile materials using polymeric core-shell particles dispersing in water. These particles are prepared from a surfactant-free emulsion polymerization according to the method of U.S. Pat. No. 6,573,313 and have average particle sizes in the range of 100 to 1000 nm in diameter. When applied to a textile article, the particles form a uniform coating, which prevents the growth of bacteria and microbes. The treatment does not affect the fabric mechanical properties, hand feeling and appearance. Antibacterial activity on cotton is maintained even after 50 times of home laundering.