The electron paramagnetic resonance of γ -irradiated single crystal of tetra-N-butylammonium iodide has been studied for different orientations of the crystals in a magnetic field. The radical produced by gamma irradiation has been investigated at 300 K. The spectra were found to be magnetic field dependent and radiation damage centers were attributed to the (C α H 2 C β H 2 C γ H 2 CH 3 ) radical. The principal values of the hyperfine coupling tensor of the unpaired electron with these atoms and the principal values of the gtensor were determined and the hyperfine coupling constants were verified by computer simulation. The results were found to be in good agreement with the existing literature data and theoretical predictions.