Oriented ZnO nanorod arrays were prepared on cotton fabrics via a simple two-step process. The ZnO nanocrystals were first synthesized and coated onto cotton substrates by dip-pad-cure process as nucleation seeds, followed by hydrothermal ZnO growth in aqueous solution of zinc nitrate hydrate and hexamethylenetetramine. Field-emission scanning electron microscope images showed the typical ZnO nanorods were 40-60 nm in diameter and 300-400 nm in length. Meanwhile, a few mesoscale ZnO nanorods with diameter of 150-200 nm, length of 600-800 nm, and their congeries were also observed on the cotton fabrics. X-ray diffraction result and Raman spectrum indicated the as-prepared nanorods were of high quality and defect free with hexagonal wurtzite ZnO structure. The as-obtained cotton sample was also characterized with energy dispersive spectroscopy and no impurities were detected. The ZnO nanorods grown on cotton fabrics possessed an ultrahigh ultraviolet protection factor of 379.14 in this study, indicating an excellent protection against ultraviolet radiation in comparison with the untreated cotton fabrics. (C) 2008 Wiley Periodicals, Inc.