he present work, among other previous studies done in our lab, aimed to highlight the histopathological effect of S. xylosus peptidoglycan in comparison to LPS of E. coli. Materials and methods: One hundred and fifty urine specimens were collected from urinary tract infection patients visiting Baghdad hospitals. The histopathological effects of S. xylosus S24 peptidoglycan was studied in the urinary tract of female mice by injecting 5 animal groups at the following concentrations: 1000, 2000, 3000, 4000, and 5000 µg/mL. Another 5 groups were injected with 10, 25, 50, 75, and 100 ng/mL of E. coli (serotype 0128:B12) LPS. Results: Ten isolates were confirmed to be Staphylococcus xylosus. Histopathological study showed different pathological changes caused by LPS and peptidoglycan, including shrinkage of glomeruli, congestion of blood vessels, and infiltration of inflammatory cells in the kidney, whereas dekeratinization and edematous dehydration of the epithelium were seen in the urinary bladder. Based on a comparison between histopathological changes caused by LPS and peptidoglycan, LPS induced changes of significantly higher severity than peptidoglycan. Conclusion: Peptidoglycan of S. xylosus had remarkable histopathological effects on the renal system of mice in a dose-dependent manner. Nevertheless, these effects had less intensity than the effects of LPS of E. coli.