PURPOSE: The treatment outcome of an intestinal obstruction depends on the early recognition and emergent operation of a strangulated intestinal obstruction. Endotoxin is a lipopolysaccharide component of the cell wall of gram negative bacteria that normally exist in the intestinal lumen. When a strangulated obstruction occurs, the endotoxin passes transluminally into the peritoneal cavity and blood stream. A disruption of the mucosal barrier is an important putative cause in this pathogenesis. This study investigated the relationship between the endotoxin level and progress of an intestinal obstruction to a strangulated obstruction. METHODS: 25 adult male Sprague-Dawley rats (200~250 g) were divided into 3 groups, the control group, simple obstruction group, and closed loop obstruction group. An intestinal obstruction was induced using a silk tie. Blood samples and obstructed bowel wall specimens were obtained at 24, 48 and 72 hours after surgery. The endotoxin and IL-6 levels were examined, and all specimens were reviewed by a pathologist for mucosal damage after H-E staining. RESULTS: In the obstruction groups, dilated bowel loops at the proximal end of the obstruction site was identified but there were no ischemic changes. The endotoxin and IL-6 levels were similar regardless of the obstruction types and times. There were no differences between the three groups in the degree of mucosal damage. However, according to the endotoxin level, the groups with an endotoxin level < 0.2 EU/ml showed mild mucosal damage. The severity of mucosal damage increased with increasing endotoxin level. CONCLUSION: There is a positive relationship (r(2)=0.673, P-value=0.002) between the endotoxin level and mucosal damage. This suggests the possibility of using endotoxin as a predictive factor for the detection of mucosal injury in an intestinal obstruction. However, a larger scale will be needed to confirm the statistical significance.