Abstract: We demonstrated the changes of the expression of IL- 1Rt I mRNA in gerbil hippocmpus after cerebral ischemia and intraperitoneal injection of MK801 by in situ hybridization histochemistry. The results showed that the expression of IL-Rt I mRNA in the pyramidal cells of gerbil hippocampus greatly increased after cerebral ischemia and the effect could be decreased to the normal level by intraperitoneal injection MK801. The result suggests that IL-1 and IL- IR might take part in the mechanism of ischemia damage in brain.