Background: Small Intestine mucosal integrity, function and barrier are defective after severe burn and because of the bacterial translocation it will end up to sepsis and death. Due to positive effects of L-arginine in wound healing during burns, the purpose of this study was to assess the effects of L-arginine to prevent the morphometric changes in small intestine of burned rats.

Materials and Methods: Twenty-four mature male rats weighting 250-270g have used in three groups. control group (n=8), burned group (n=8) and burn with L-arginine (100 mg/kg intra peritoneal on 1, 3 and 5 days after burn). For burning induction, after general anesthesia and shaving, a selected area of the back region (5×3.5cm) was exposed to boiling water for 8 seconds in order to produce the wet burns. On the 7th day after burn specimens from the first part of small intestine were obtained. After fixation and staining the samples with Hematoxiline and Eosin villi height, small intestine diameter and its lumen diameter, muscular layer thickness, and crypt depth were measured.

Results: Villi height, crypt depth of small intestine mucosal was significantly decreased in burned group compared with other groups. The structure of the small intestine in L-arginine group was similar to control (normal) group.

Conclusion: The results showed that L-arginine prevented from villi atrophy and also morphometric changes of small intestine mucosal and prevented pathological changes during burn.