Microglia play a crucial role in neuroinflammation after ischemic brain injury. Previous data have shown that leukocyte immunoglobulin-like receptor B4 (LILRB4) was upregulated in mice after middle cerebral artery occlusion (MCAO), but the role it plays here is not well understood. The role LILRB4 plays in ischemic brain injury was thus investigated. LILRB4 expression was measured in mice at different time points after MCAO.