Object To collect and summarize high quality clinical evidence on the use of hyperbaric oxygen (HBO) in health care generally. Method We searched MEDLINE (1980-2006), The Cochrane Library (Issue 1, 2006) and the China Biomedicine Database (1982-2006) for systematic reviews, meta-analyses and randomized controlled trials. The quality of included studies was critically evaluated. Result Thirteen systematic reviews (12 Cochrane reviews) on HBO were included. Results showed that HBO had some beneficial effect on acute coronary syndrome, ischemic stroke, multiple sclerosis, malignant otitis externa, idiopathic sudden sensorineural hearing loss and tinnitus. It might also promote chronic wound healing and relieve radiation damage.Conclusions Since the avaliable randomized controlled trials for the systematic reviews we included are too small, further well-designed multicentre large-scale trials are needed to determine the efficacy and safety of HBO .