The effects of 4.5-Mev electron bombardment on the electrical properties of n- and p-type InSb are studied. Isochronal annealing experiments carried out on samples bombarded at 80°K indicate three regions of rapid annealing, the first two between 80°K and 200°K and the third near room temperature. It is shown that the distribution of bombardment-produced energy levels is altered by heating a bombarded specimen to 200°K. The changes which occur as a result of this heat treatment suggest that energy levels are shifted as defects rearrange themselves into positions of greater stability. For samples bombarded at 200°K, the positions of energy levels and the rates at which they are generated are determined from careful studies of the rates at which they are generated are determined from careful studies of the temperature dependence of carrier concentration. Mobility changes are utilized to identify donor or acceptor behavior. The levels introduced into the forbidden band appear to be multiply ionized.