114 patients with peripheral nerve injury were treated microsurgically. 54 patients with 65 nerve injuries were given hyperbaric oxygen as supplementary treatment. The excellent and good results of the 65 nerves accounted for 89.2%, but of those nerves in patients not treated with hyperbaric oxygen for 73.2% (P less than 0.05). The result was better in the hyperbaric oxygen group regardless of the repairing method used, particularly in those nerve grafting had been done (24.9, P less than 0.05). As for the time lapsed from injury to surgery. The results of fresh injuries showed no difference in either group, but hyperbaric oxygen was of much benefit to the old cases: the longer the delay the greater in difference between different groups, but better results were obtained in the hyperbaric oxygen group. The early the operation the better the result in either group.