A controlled clinical trial is in progress to assess the value of hyperbaric oxygen and radiotherapy in the management of head and neck cancer. An established dose-fractionation schedule in hyperbaric oxygen is being compared with a widely used conventional schedule in air. Survival and local recurrence-free rates are significantly higher in the oxygen group, and the effects on normal tissue are similar in both groups. These findings suggest a genuine therapeutic advantage. There was a distinct improvement in the results of treating advanced laryngeal carcinoma, where there was a high survival rate, without resort to laryngectomy.