Abstract： Objective To explore effect of hyperbaric oxygen therapy on dysbaric osteonecrosis.Methods Thirteen male patients with dysbaric osteonecrosis were given hyperbaric oxygen therapy, and symptoms and changes in X-ray films were compared pre and post HBO therapy. Results In the 13 cases,pathological changes due to osteonecrosis were detected in femur, humerus and cnemis, with femoral head/neck and humeral head being the most common sites. The therapeutic effect of HBO was closely related with the course of HBO therapy. Conclusions HBO therapy had positive effects on dysbaric osteonecrosis, however,long and regular treatment was the key to the enhancement of a desirable therapeutic effect.