We describe a 68-year-old man who underwent hyperbaric oxygen (HBO) therapy to manage radiation necrosis of the brain, which developed after two treatments with stereotactic radiosurgery (SRS) to the same lesion. The necrosis was subsequently treated with steroids alone for 2 months; however, he progressed clinically and radiographically. Improvement again was noted with the reinstitution of HBO therapy. This case suggests that HBO therapy is an important therapeutic option in the treatment of brain radiation necrosis caused by SRS.