Cycloastragenol (5, 10, 20 mg/kg) is injected intraperitoneally at the onset of reperfusion, 12 h later and then twice daily for up to three days. Cycloastragenol dose-dependently reduces brain infarct volume, significantly ameliorated functional deficits, and prevents neuronal cell loss in middle cerebral artery occlusion (MCAO) mice. Cycloastragenol suppresses the mRNA expression of pro-inflammatory cytokines, including TNF-α and IL-1β, and inhibits the activation of microglia and astrocytes in the ischemic brain.