Objective To evaluate the role of heparanase in endotoxemia-induced destruction of vascular endothelial glycocalyx in rats. Methods Forty-eight pathogen-free male Sprague-Dawley rats, aged 8-10 weeks, weighing 200-250 g, were randomly divided into 3 groups(n=16 each)using a random number table: control group(group C), lipopolysaccharide(LPS)group(group L)and LPS+ heparin group(group LH). Endotoxemia was induced by intravenous LPS 15 mg/kg in L and LH groups, and heparin sodium 100 U·kg-1· h-1 was infused simultaneously in group LH.At 3 and 6 h after LPS injection, blood samples were collected from the femoral vein for determination of the serum concentrations of serum heparin sulfate(HS), syndecan-1, E-selectin and intercellular adhesion molecule-1(ICAM-1)concentrations.The rats were then sacrificed, and lungs were removed for microscopic examination and for determination of wet/dry lung weight ratio(W/D ratio). Results Compared with group C, the serum HS, syndecan-1, E-selectin and ICAM-1 concentrations and W/D ratio were significantly increased in group L, and the serum HS and ICAM-1 concentrations were increased in group LH(P<0.05). Compared with group L, the serum HS, syndecan-1, E-selectin and ICAM-1 concentrations and W/D ratio were significantly decreased in group LH(P<0.05). The pathological changes of lungs were obvious in group L, and were significantly mitigated in group LH. Conclusion Heparanase is involved in endotoxemia-induced destruction of vascular endothelial glycocalyx in rats. Key words: Heparin lyase; Endotoxemia; Glycocalyx; Endothelial cells