Objective: To observe the expression of DNA damage and repair gene: GADD45 following cerebral ischemia in aged rats, and to investigate the effects of Kadsurenone on the expression of GADD45 and neuronal cell apoptosis. Methods: Wistar rats of 26-month-old with focal cerebral ischemia were administered herb Kadsurenone. The change of GADD45 protein expression was determined with immunohistochemistry, and the neuronal cell apoptosis with TUNEL staining techniques. Results: Few GADD45 response positive cells existed in the core of ischemic area 4 hours after ischemia, but a great deal expressed in the peripheral area, which was significantly different from the control group(P<0.05). GADD45 response positive cells at 24 hours were fewer than those at 4 hours, but higher than those in pseudo-surgery group(P<0.05). TUNEL positive cells in herb Kadsurenone group increased compared with pseudo-surgery group(P<0.05), but decreased compared with 24-hour ischemia control group (P<0.05). GADD45 positive cell of herb kadsurenone group increased compared with control group (P<0.05) and pseudo-surgery group (P<0.01). Conclusions: Kadsurenone, an inhibitor of PAF has protective effect on cerebral ischemia, and it can decrease the extent of DNA damage and up-regulate the expression of GADD45, a DNA repair gene.