Hyperbaric oxygen has been shown to improve oxygen tension and promote wound healing. We did a pilot study in which we created ischemic jejunal segments measuring 3, 6, and 9 cm, 10 of each length, in 30 rats. Half of the rats were given hyperbaric oxygen at 100%, 30 psi, for 90 minutes twice daily for 7 days to determine whether hyperbaric oxygen therapy could overcome the ischemic intestinal injury and prevent ischemic necrosis. In the rats with 6- and 9-cm ischemic segments, no difference was seen between the hyperbaric oxygen and control groups. Of the rats with 3-cm ischemic segments, ischemic infarction of the bowel developed in 40% of the hyperbaric oxygen group and 100% of the controls (P = 0.167, Fisher's Exact Test). We then created 3-cm ischemic intestinal segments in 30 additional rats. Again, half were treated with hyperbaric oxygen as previously described for 7 days. There was no difference between the controls and the hyperbaric oxygen group in the rate of perforation (4 of 15 [27%] versus 1 of 15 [7%]) or stricture rate (8 of 15 [53%] versus 9 of 15 [60%]). We concluded that hyperbaric oxygen therapy is of limited value for the treatment of intestinal ischemias.