Hyperbaric oxygen therapy is the administration of 100% oxygen at pressures two to three times ambient pressure, and it significantly increases dissolved oxygen content. Although it has been used successfully to treat decompression illness and arterial air embolism, its role in the treatment of carbon monoxide poisoning remains somewhat controversial. Published evidence and guidelines for the use of hyperbaric oxygen therapy in carbon monoxide-poisoned infants and children are scarce compared with those available for carbon monoxide-poisoned adults. Because of their higher metabolic rates and developing nervous systems, infants and children may be more susceptible to the effects of carbon monoxide and also may warrant special considerations. This review focuses on the unique aspects of carbon monoxide poisoning and hyperbaric oxygen therapy in the fetus, the newborn, the infant, and the child. In addition, it discusses general indications for and special and practical considerations in the use of hyperbaric oxygen therapy in children.