Various studies of the effect of hyperbaric oxygen (HBO) in a wide variety of disease entities have been carried out. In the treatment of burns, animal and human studies have yielded somewhat contradictory results. Controlled studies in humans are limited. A randomized study on the effect of HBO was conducted involving 125 burn patients admitted within 24 hours of injury who were matched by age, burn size, and presence or absence of inhalation injury. Patients in the treatment arm received oxygen at two atmospheres of pressure for 90 minutes twice a day for a minimum of 10 treatments and a maximum of one treatment per total body surface per cent burn. The control group was treated in a similar fashion, except for the absence of HBO. There were no statistically significant differences between the two groups for the outcome measures of mortality, number of operations, and length of stay for the survivors. In this large clinical trial, we were unable to demonstrate any significant benefit to burn patients from the use of HBO.