Epitaxial ReSi2thin films grown on Si (100) substrates were analyzed at room temperature by MeV 4He backscattering and channeling spectrometry. The minimum yield of [100] axial channeling increases with increasing exposure of the ReSi2sample to the analyzing He beam. This means that ReSi2suffers irradiation damage induced by a MeV 4He beam. The damage in the film induced by a beam incident along a random direction is about one order of magnitude larger than that induced by a beam with an aligned incidence, indicating that the damage is mainly generated by elastic collisions of nuclei. The experimentally measured defect concentration produced at 300 K by a beam of random incidence is compared with the theoretically estimated one produced at 0 K in an amorphous target. The agreement is fairly good, suggesting that the defects are stable at room temperature.