OBJECTIVE: To investigate the effect of baicalin, a flavonoid extracted from the radix of  Scutellaria baicalensis Georgi, on the expression of nuclear factor (NF) κB/IκBα induced by hydrogen peroxide (H 2O 2) in astrocytes. METHODS: Astrocytes were cultured in vitro, and treated with various concentrations of baicalin or/and H 2O 2. Immunocytochemistry was used to determine the translocation of P65 from cytoplasm to nucleus; and Western Blot was used to determine the expression change of IκBα in astrocytes. RESULTS: In astrocytes, H 2O 2 could induce the translocation of P65, a subunit of NF κB, from cytoplasm to nucleus, and reduce the level of IκBα expression, while baicalin could inhibit this effect. CONCLUSIONS:Baicalin may decrease the degree of IκBα degradation and NF κB activation induced by H 2O 2 in astrocytes.