The influence of radiation damage on the fatigue performance of two selected copper alloys, a dispersion-strengthened CuAl-25 alloy and a precipitation-hardened CuCrZr alloy, was analyzed. The fatigue lives of the two alloys were predicted using their tensile properties before and after irradiation by the Universal Slopes method. The predicted lives are compared with experimental results, and the feasibility of using tensile properties to predict fatigue lives following irradiation is examined. The fatigue performance of these two copper alloys was degraded due to radiation exposure, but the radiation effect on the fatigue performance was not as severe as on the tensile properties. The life prediction agrees reasonably well with the measured fatigue response.