INTRODUCTION AND AIMS: Bacterial peritonitis is a frequent complication during treatment of end-stage kidney disease by Peritoneal Dialysis (PD); severe or repeated episodes of peritonitis cause long-term complications that potentially lead to peritoneal membrane failure. Lipopolysaccharide (LPS) or endotoxin is an abundant glycolipid present on the outer membrane of Gram-negative bacteria and it may contribute to the progression of a local infection to sepsis. Previous studies demonstrated that LPS level is related to the degree of systemic inflammation and atherosclerosis in PD patients. The aim of this study was to evaluate LPS levels in PD patients, in particular, we investigated LPS levels in PD with Gram positive/ negative peritonitis.