Background. We aimed to investigate the effects of hyperbaric oxygen therapy on bacterial translocation and acinar cell ultrastructure in a rat model of acute necrotizing pancreatitis. Methods. Forty-eight male Sprague-Dawley rats were randomly divided into three groups. Acute pancreatitis was induced in groups II and III. Groups I and II did not receive any treatment, and group III was treated with hyperbaric oxygen. All surviving animals were killed 48 h after the induction of pancreatitis. Bacterial translocation and histological and ultrastructural changes were determined. Results. The incidence of bacterial translocation in group III was significantly lower in comparison with group II (P < 0.001). Histopathological and ultrastructural injury scores were also significantly lower in group III (P < 0.001 and P < 0.04, respectively). Conclusions. Hyperbaric oxygen therapy displayed beneficial effects on pancreatic superinfection and or histopathological and ultrastructural changes in experimental necrotizing pancreatitis.