Background: Currently, there is no method of accurately diagnosing bacterial translocation (BT) in humans. BT may be related to changes in intestinal permeability. In this study, we examined the correlation between intestinal permeability using polyethylene glycol (PEG) 4000 and BT. Materials and Methods: Under general anesthesia, laparotomy was done in rats, and PEG4000 was administered to the small intestine. We prepared models of invasive stimulation in which lipopolysaccharide (LPS) was intravenously administered, and a hemorrhagic shock model in which blood pressure was decreased to 30 mm Hg. Blood PEG4000 levels were measured. We also measured blood PEG levels in a model in which oxygen was administered to treat hemorrhagic shock. In all models, the presence or absence of BT development was evaluated. Results: In groups given LPS, mean blood PEG levels were significant higher than in the group treated with saline solution. In the hemorrhagic shock group, the mean PEG level was increased but was slightly inhibited by oxygen administration. In the LPS and hemorrhagic shock groups, the incidence of BT was significantly greater than in the control group. In the hemorrhagic shock group, the incidence of BT was 0% after oxygen administration. There was a correlation between the incidence of BT and changes in the intestinal permeability of PEG4000 (R-2 = 0.824). Conclusions: LPS stimulation enhanced intestinal permeability in a dose-dependent manner. An increase in intestinal permeability was correlated with the incidence of BT. Blood PEG4000 levels correlated positively with the grade of invasion and the incidence of BT. Copyright (C) 2000 S. Karger AG. Basel.