At Duke University Medical Center, 49 patients with proved clostridial myonecrosis were treated with hyperbaric oxygen (HBO) during the past 10 years. Survival in patients with involvement confined to the extremities was 92.3 percent. Survival in patients with combined involvement of extremity and trunk was 53-3 percent, and with primary trunk involvement half of the patients survived. Survival for the entire series was 73.5 percent. Among the 28 patients receiving at least five HBO treatments, 24 survived. Extensive experimental studies were conducted during this same period including in vitro testing and in vivo experimental infections with C. perfringens. Data from the experimental models of gas gangrene indicate a therapeutic benefit with HBO by significantly decreasing both mortality and morbidity rates. The mechanism of action for this appears to be complex but probably includes a direct bactericidal action, bacteriostasis, inhibition of toxin production, and improvement in tissue oxygenation. In the absence of a controlled study, the therapeutic efficacy of HBO in the treatment of clostridial myonecrosis is not fully proved. Nevertheless HBO treatment can be recommended on the bases of sound experimental evidence and the results of favorable clinical experience. Mitigation of this severe but infrequent illness can best be accomplished through prevention, with strict adherence to the principles of wound care.