Introduction: Hyperbaric oxygen therapy (HBO) is emerging as an alternative technique for treating refractory interstitial cystitis (IC). The theory is that the increased dissolved oxygen in the blood raises the levels of oxygen in the tissues and improves tissue healing. Other urological disorders such as radiation cystitis, Fournier’s gangrene and cyclophosphamide cystitis have also shown a good response to HBO therapy. Method: A literature search with the terms “interstitial cystitis”, “painful bladder syndrome” and “hyperbaric oxygen therapy” found four papers that have trialed HBO therapy in IC patients; three case series and one randomized control trial. Results: A total of 31 patients have been treated with HBO therapy. All four studies show a symptomatic improvement in pain, urgency, bladder capacity and O’Leary-Sant interstitial cystitis index. Urinary frequency only improved in three out of four of the trials. The percentage of patients considered as responders to treatment varied at 25%, 66.7%, 82% and 100%. Conclusion: Preliminary trials of HBO therapy seem to have a good patient response with effective symptomatic relief. The patient response rates varied greatly between the trials. This is due to each trial’s different definition of a “patient responder”. Further work in urology departments at HBO centers is required to further assess the benefits of HBO treatment in IC.