Graft copolymer of natural rubber (NR) and polystyrene was successfully prepared by electron beam irradiation for the first time. The experiments were designed based upon the Taguchi method, using Minitab software, in order to reduce the number of experiments. The radiation dose was varied from 25 to 100 kGy. The content of sensitizer (n-BA) was varied from 0 to 5 phr. Various NR/St ratios were used: 90:10, 80:20, 70:30, and 60:40. Characterization of graft copolymer was confirmed by Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) techniques. The core-shell structure of graft copolymer was obtained and the monomer conversion, grafting efficiency, grafting yield, and crosslink density were studied. Optimum conditions were determined by the experimental design: radiation dose of 75 kGy, content of n-BA of 5 phr, and NR/St ratio of 80: 20. Finally, the tensile strength of latex films was found to be significantly related to the studied factors. (C) 2015 Elsevier Ltd. All rights reserved.