Ｏｂｊｅｃｔｉｖｅ　To investigate the effect of dexmedetomidine(Dex) on inflammatory response and postoperative cognitive dysfunction(POCD) after general anesthesia.　Methods　Sixty patients with ASAⅠ-Ⅱ and aged 60-75 y, undergoing the selective abdomen surgery with general anesthesia, were randomly assigned into 2 groups(n=30): Dex group(group D) and control group(group C). All patients in Both groups received 0.03-0.05 mg/kg of midazolam, 2-3 μg/kg of fentanyl, 0.5-1.5 mg/kg of propofol and 0.15 mg/kg of cisatracurium during anesthesia induction. The patients in group D were intravenously given Dex(1 μg/kg) for 10 min before induction, followed by 0.2-0.7 μg·kg-1·h-1 maintenance, while patients in group C were administrated the same volume of 0.9% NS and the infusion rate could be adjusted according to patients'vital signs. Blood samples were collected from the central venous to determine the plasma IL-6 level and activation of NF-κB in neutrophils before induction of anesthesia(T1), at the end of operation(T2), 24 h after operation(T3). Neurocongnitive outcome was evaluated by mini-mental state examination(MMSE) and abbreviated mental test(AMT) at 1, 2 d before operation and at 1, 3, 7 d after operation.　Results　13 of 60 patients(21.67%) performed with POCD, including 3 patients in group D and 10 patients in group C(P<0.05). Compared with T1, the activation of NF-κB in neutrophils in both groups increased significantly at T2 and T3(P<0.05) , and was lower in group D than it in group C(P<0.05). The level of IL-6 at T2 was significantly higher than that at T1 and T3 in both groups (P<0.01), and was lower in group D than it in group C at T2(P<0.01). In group D, NF-κB activation in neutrophils was positively correlated with plasma IL-6 level(r=0.65, P<0.01).　Conclusions　The incidence of POCD was correlated with oxidative stress. Inhibition of NF-κB activation may be helpful to attenuate inflammatory cytokines in aged patients undergoing abdomen surgery with general anesthesia and reduce the incidence of POCD.