Recently, the treatment of stroke has focused on antioxidant therapies, where oxidative stress is implicated The preventive and therapeutic potential of plant compounds on ischemic stroke has been intensively studied because many of them contain antioxidant properties. Genistein, one of the active ingredients in soybean, possesses many bioactivities. In this study, we investigated the potential neuroprotective effects of genistein and its possible mechanism of action in a cerebral ischemia mouse model Mice were pretreated with genistein (2.5, 5 and 10 mg/kg) or vehicle orally once daily for 14 consecutive days before transient middle cerebral artery occlusion was performed. Genistein at doses of 2.5—10 mg/kg significantly reduced the infarct volume. improved the neurological deficit and prevented cell apoptosis after ischemia. In addition. genistein pretreatment was shown to inhibit the ischemia-induced reactive oxygen species (ROS) production, enhance the activities of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx). and decrease levels of malondialdehyde (MDA) in stroke mice. Moreover, genistein reversed the mitochondrial dysfunction after ischemia. as evidenced by decreasing mitochondria ROS levels, preventing cytochrome C release to the cytoplasm and inhibiting caspase-3 activation. Western blotting showed ischemia activated the ROS-dependent nuclear factor-kB (NF-kB) signaling pathway, and genistein suppressed phosphorylation and activation of the NF-KE p65 subunit. as well as the phosphorylation and degradation of the inhibitor protein of kBa(IkBa). Our findings suggested that genistein has a neuroprotective effect in transient focal ischemia, which may involve regulation of mitochondria-dependent apoptosis pathways and suppression of ROS-induced NF-kB activation.