Pure Zr and Zr–Sn (0.015 at. % to 2.3 at. % Sn) allOáys were irradiated at 4.6 K to a fast neutron fluence of 2.5 × 1022neutrons m−2and the radiation-induced resistivity was measuredin situas a function of dose. Compared to pure Zr the initial damage rate was higher in Zr—Sn alloys, whereas the saturation resistivity was found to remain almost constant. The samples were subjected to isochronal annealing in the temperature range of 30—509 K and the different recovery stages studied. The addition of tin suppressed the recovery in stage I and stage III.