Objectives: To compare success, morbidity, patient satisfaction and cost effectiveness of dental implant treatment carried out with and without hyperbaric oxygen (HBO) therapy in irradiated patients. Data sources: MEDLINE, EMBASE, The Cochrane Oral Health Group's Trials Register, and The Cochrane Central Register of Controlled Trials (CENTRAL) to June 2007. Review methods: Systematic review with search without language restriction for randomised clinical trials only. Quality assessment of identified trials according to Cochrane Handbook for Systematic Reviews of Interventions. Results: We identified one RCT measuring dental implant outcomes in patients who had received radiotherapy. Twenty-six patients were randomised to HBO therapy or no HBO therapy. There were no statistically significant differences by group for prosthesis or implant failure, preimplantation or postimplantation complication, or patient satisfaction. This trial had a high risk of bias. Conclusions:We were unable to find any strong evidence to either support or refute the use of HBO therapy for improving the implant outcome for patients who have received radiotherapy. We would recommend that more RCTs are undertaken to provide better evidence for decision making by clinicians. Meanwhile, clinicians should be aware of the limited availability of evidence and should therefore provide patients with the appropriate information about the potential benefits and harms of HBO therapy as part of the consent process. Schlagwörter: dental implants, hyperbaric oxygen therapy, irradiation