Objective To study the correlation between the expression of intercellular adhesion molecule 1(ICAM 1) and leukocyte infiltration, and explore the effects of mild hypothermia.Methods ICAM 1 positive expression and leukocyte infiltration in the ischemic regions were determined using immunohistochemitry and histological HE staining techniques at different reperfusion time(2 h,8 h,24 h,48 h and 72 h) after middle cerebral artery occlusion (MCAO) for 3h in rats, and mild hypothermia was given after MCAO followed by 24h reperfusion.Results (1)The expression of ICAM 1 raised obviously 2h after cerebral ischemia reperfusion, and peaked at 24h ( P