Previous studies have demonstrated that plasma resistin levels were increased in patients with acute ischemic stroke. However, the role of resistin after ischemic brain injury is still unclear. In this study, we investigated the protective effects of resistin on cerebral ischemia/reperfusion injury in a middle cerebral artery occlusion mouse model. We found that resistin (i.c.v.) significantly reduced infarct volume and improved neurological deficits after 45 min of ischemia and 24 h of reperfusion. Furthermore, our data demonstrate that intraperitoneal administration of resistin (10 mu g/kg body weight) also had protective effects on infarct volume, indicating the crossing of resistin through the impaired BBB after ischemia injury. Resistin treatment reduced cleaved protein level of Poly(ADP-ribose)polymerase-1 (PARP-1), a marker of cellular apoptosis, showing the anti-apoptotic activity of resistin. Resistin increased the level of phosphorylated Akt after ischemic brain injury. The neuroprotective effect of resistin was partially reversed by a PI3K inhibitor wortmannin, demonstrating that the PI3K/Akt signal pathway is involved in the anti-apoptotic mechanisms of resistin. Finally, we found that resistin treatment improved neurological function recovery at 14 days after treatment, including balance ability and muscle strength. Given these findings, resistin may have therapeutic potential for the treatment of stroke.