We used 2 MeV4He backscattering spectrometry, x‐ray diffractometry, and the van der Pauw technique to study how epitaxial ReSi2films on Si(100) change structurally and electrically upon room‐temperature implantation of 300 keV28Si or 380 keV40Ar. The as‐grown film has a minimum channeling yield of ∼2% for Re, and a resistivity of ∼23 m&OHgr;cm at room temperature. Ion implantation produces damage in the film, which increases monotonically with dose. At a dose of either 5×101428Si/cm2or 1×101440Ar/cm2, the entire ReSi2film becomes both x‐ray and channeling amorphous. The resistivity of the film decreases monotonically with dose. The amorphous film has a resistivity of ∼1.2 m&OHgr;cm at room temperature. Upon annealing in vacuum at 700 °C for 30 min, the damage anneals out and the amorphous ReSi2film recrystallizes epitaxially, once again exhibiting a minimum channeling yield of ∼2% for Re and a resistivity of ∼23 m&OHgr;cm.