Surface bromination of low-density polyethylene (LDPE) was carried out by brief exposure to gaseous bromine followed by UV irradiation. X-ray photoelectron spectroscopy suggests two different types of C-Br groups. Atomic force microscopy and wetting studies reveal that excessive bromination is accompanied by severe surface roughening. A nucleophilic substitution reaction was used to introduce surface 4-aminobenzenethiolate functionalities. UV spectral analysis indicates a grafting density of 2.9 bromine atoms per 100 Angstrom(2) for the first bromination cycle.