Poly(ethylene terephthalate) fibers containing zinc chloride in the fiber bulk were prepared by solvent crazing. Fibers containing 6 g/Kg and 1.3 g/Kg Zn2+ were investigated. SEM-EDX analyses and the formation of the pink bis(1,5-dithiocarbazonato-N,S) complex inside the fibers confirm the presence of zinc. UV-Vis spectroscopy indicates a slow release of zinc ions into the aqueous media and, thus, the fibers serve as a release system to inhibit the growth of Escherichia coli during the first exposure. Thermal annealing of the freshly prepared fibers above T, was shown to modify the release profile so that bacterial growth was also inhibited during repetitive and prolonged exposures. The washing fastness is fair and after 10 washing cycles, similar to 30% of the original zinc content still remains in the fiber. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112:2634-2640, 2009