In this study, the antifelting and antibacterial features of wool samples treated with nanoparticles of titanium dioxide (TiO(2)) were evaluated. To examine the antifelting properties of the treated samples, the fabric shrinkage after washing was determined. The antimicrobial activity was assessed through the calculation of bacterial reduction against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. TiO(2) was stabilized on the wool fabric surface by means of carboxylic acids, including citric acid (CA) and butane tetracarboxylic acid (BTCA). Both oxidized samples with potassium permanganate and nonoxidized wool fabrics were used in this study. The relations between both the TiO(2) and carboxylic acid concentrations in the impregnated bath and the antifelting and antibacterial properties are discussed. With increasing concentration in the impregnated bath, the amount of TiO(2) nanoparticles on the surface of the wool increased; subsequently, lower shrinkage and higher antibacterial properties were obtained. The existence of TiO(2) nanoparticles on the surface of the treated samples was proven with scanning electron microscopy images and energy-dispersive spectrometry. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 3407-3413, 2011