Objective:To observe the effects of endotoxin tolerance on the production of inflammatory cytokine TNF-α and anti-inflammatory cytokine IL-10 in THP-1 cells. Methods:THP-1 cells were pretreated with 1 μg/ml Porphyromonas gingivalis (P.gingivalis) lipopolysaccharides (LPS) or 1μg/ml Escherichia coli (E.coli) LPS for 24 h. Then,the cells were washed and stimulated with the same LPS for additional 24 h. The levels of TNF-α and IL-10 in supernatants were detected by ELISA. Results:The amounts of TNF-α and IL-10 secreted by THP-1 cells stimulated with P.gingivalis LPS or E.coli LPS were increased significantly after 24 h (P < 0.05). After restimulations for another 24 h,TNF-α production was decreased significantly compared with that secreted by the cells stimulated with the same LPS only once(P < 0.05),while the level of IL-10 was increased significantly(P < 0.05). Conclusion:Repeated LPS stimulations triggered endotoxin tolerance and led to a decrease in TNF-α production and an increase in IL-10 production,which might have effects on periodontal inflammation.