The amount of damage present in germanium (and silicon) following : mplants of 200 keV H+or 300 keV D+at temperatures between 40–300°K has been measured using the channeling technique. The damage level is observed to increase strongly with decreasing implantation temperature. Damage profiles were obtained from the data by considering various scattering mechanisms, including single and plural scattering and a steady increase approximation treatment. For equal dose implants, deuterons create considerably more damage in germanium than protons. The ratio of deuteron damage to proton damage is significantly greater than the ratio of energy deposited in nuclear events for the two ions. The results of isochronal anneals at temperatures from 40 to 325°K on Ge crystals implanted at 40°K are also reported. A strong annealing stage is observed around 175°K; this is in good agreement with previous optical absorption studies of proton damage in germanium.