Objectives This review aims to highlight the advantages and safety of oxygen-ozone therapy (OOT) and to suggest ways to enhance its acceptance. Key findings The treatment of a herniated disk by injecting a gaseous oxygen-ozone mixture inside the nucleus pulposus is a great clinical success. However, the use of OOT lags for a number of reasons, including lack of standardization, the need for numerous treatments, lack of knowledge and even denial. Anecdotally, several million treatments by OOT have been performed worldwide indicating its usefulness, mainly in peripheral arterial diseases and age-related macular degeneration. The scepticism that accompanies the systemic use of ozone can only be overcome by demonstrating the validity of OOT in controlled and randomized clinical trials. Cheaper and quicker methods, such as ozonating physiological saline with successive infusion as well as ozone rectal insufflations, are becoming popular, however, such alternative procedures are erratic, unstable and liable to be toxic, with deleterious consequences, and are likely to discredit the beneficial use of ozone. Summary The approval of ozone in terms of both therapeutic efficacy and safety will depend on the results achieved by authoritative clinical trials.