Objective · To investigate the effect of genistein (Gen) on lipopolysaccharide (LPS)-induced proinflammatory response in microglia. Methods · Primary microglia were isolated C57BL/6J mice 1 d after birth, which were divided into 3 groups, i.e. control group, LPS group, and Gen+LPS group. Microglia in LPS group and Gen+LPS group were incubated with LPS (1 μg/mL) for 24 h, and the cells in Gen+LPS group were also pretreated with Gen (10 μmol/L) for 0.5 h. The of CD11b was measuredWestern blotting analysis. Besides, mitochondrial and intracellular reactive oxygen species (ROS) levels were monitoredMitoSOXTM Red and CM-H2DCFDA staining, respectively. NLRP3 (NLR family pyrin domain containing 3) inflammasom was detectedimmunofluorescence. Caspase-1 activity and interleukin-1β (IL-1β) levels were evaluatedcolorimetric assay kit and ELISA kit, respectively. Results · Compared with control group, LPS increased CD11b protein , and mitochondrial and intracellular ROS levels in microglia (P<0.05). And Gen obviously reversed LPS-induced mitochondrial and intracellular ROS accumulation as well as reduced CD11b (P<0.05). In addition, LPS enhanced fluorescence intensity of NLRP3 inflammasome, caspase-1 activity and IL-1β secretion in microglia when compared with control group (P<0.05), while Gen significantly attenuated these effects (P<0.05). Conclusion · Gen can inhibit LPS-induced proinflammatory response including mitochondrial ROS accumulation, activation of NLRP3 inflammasome, and IL-1β secretion in microglia.