In this Phase II feasibility prospective clinical trial, we propose to recruit and enroll 70 brain-injured subjects and expose them daily to hyperbaric oxygen at 1.5 atmospheres absolute for 60 minutes per session, for 60 sessions per subject. This research protocol is the one most commonly used by practitioners who claim benefit with hyperbaric oxygen therapy. Before and after the 60 hyperbaric oxygen sessions, and at 6 months following completion of hyperbaric oxygen, outcome measures consisting of neuropsychological testing, functional measures, health-related quality of life measures, and a neurological examination will be conducted and analyzed with the subjects serving as their own controls. Important information regarding a subsequent Phase III clinical trial, including subject recruitment, tolerance and risk of therapy, dropout rate, and potential benefit or lack of benefit with hyperbaric oxygen will be reported.