Aim To evaluate the effect of lipopolysaccharide on human monocytes tumor necrosis factor α production and nuclear factor kappa B activation. Methods Monocytes were isolated by Ficoll density gradient from blood of healthy volunteers. The amount of tumor necrosis factor α protein in culture medium was quantified by using tumor necrosis factor α ELISA systems. Nuclear factor kappa B translocation in monocytes was observed by immunohistochemistry assay. Results We find that nuclear factor kappa B was activated after being stimulated for 15 minutes and reached peak at 1 hour. Lipopolysaccharide (1 μg/L～1 mg/L) induced monocytes tumor necrosis factor α production in a dose-dependent manner. Tumor necrosis factor α protein in medium could be detected at 1 hours, and achieve peak at 6 hour. Nuclear factor kappa B activation before tumor necrosis factor α production in monocytes. Conclusions Lipopolysaccharide induced pro-inflammation cytokine production at least in part through nuclear factor kappa B activation in monocytes.