Radiation‐induced degradation in packaged metal–oxide semiconductor field effect transistors (MOSFETs) can be efficiently removed by an anneal treatment carried out at 350 °C for 10 min in N2. The electrical characteristics of the MOSFETs including threshold voltageVth, transconductanceGm, and drain currentIdwere examined in the recovery of device performance. The irradiation was performed by a Co‐60 (γ‐ray) source with the irradiation total doses ranging from 10 K rads to 10 M rads. Experimental results show that the anneal treatment can be repeatedly performed on a sample after receiving multiple irradiation and the recovery behavior is quite good for each anneal treatment. The determination of the temperature and the anneal time are also discussed.