Hyperbaric oxygen (HBO) treatment is the inhalation of 100 % oxygen under pressure greater than I atmosphere (atm) in a closed chamber, (1 atm: 760 mmHg). In this experimental study, the effect of HBO treatment on bacterial translocation (BT) in intestinal obstruction was investigated on rats. In 103 female Wistar-Albino rats, five groups were designed as follows: Group 1, control; group 2, rats with laparotomy; group 3, rats with laparotomy+HBO treatment; group 4, rats with intestinal obstruction; group 5, rats with intestinal obstruction+HBO treatment. Each group, excluding the control, was divided into 24, 48 and 72 hour subgroups. BT to mesenteric lymph nodes and blood was evaluated according to the aerobic and anaerobic cultures. It was determined that BT was mainly caused by gram-negative microorganism in all groups; and E. coli was the most common microorganisms isolated in groups without HBO treatment while it was P. mirabilis in groups with HBO treatment. It was also found that the effect of HBO treatment was most meaningful in the first 24 hours and when the obstruction groups (group 4 and 5), were compared with each other; in all subgroups, the difference between the growth of the blood cultures was significant (p<0.05). It was concluded that, HBO treatment shows this effect primarily by decreasing the intraluminal gas and dilatation while preventing the intraluminal bacterial overgrowth, and increasing the surface area of perfused capillaries by increasing the partial pressure of oxygen and bacteriostatic, bactericidal and immune system supportive effects of HBO also strengthen the basic effect.