Objective A growing body of evidence indicates that neuroinflammation characterized by microglial activation probably contributes to the pathogenesis of Parkinsons disease (PD), and the mechanisms underlying microglial activation in PD are largely unknown.Our study is to explore whether aggregated α-synuclein can activate microglia and the mechanism underlying that.Methods The activation ofmicroglia was measured by morphological changes, neurotoxic factor production, and phagocytotic activity in BV2 ceils as well as primary cultured rat microglia treated with aggregated α-synuclein.Results Aggregated α-synuclein clearly changed microglial morphology and enhanced microglial production of extracellular NO, mRNA levels of IL-1β, IL-6, COX-2, iNOS and phagocytotic activity.Conclusion Aggregated α-synuclein can induce microglial activation, and the underlying mechanisms are under study.