&ggr;‐ray irradiation with doses up to 8 × 106rad produces no significant change on either theC(V) or theG(V) characteristics of MOS tunnel junctions with intermediate oxide thicknesses (40–60 Å), whereas the expected flat‐band shift toward negative electrode voltages occurs in control thick oxide capacitors. A simple tunneling model would explain the results if the radiation‐generated hole traps are assumed to lie below the valence band of the silicon. The experiments also suggest that the observed radiation‐generated interface states in conventional MOS devices are not due to the radiation damage of the silicon surface.