Objective：To investigate the effect of inhaled ketamine on airway hyperresponsiveness in allergic asthma rats. Methods：Forty male Brown Norway rats were randomized into five groups:control group C,asthma groups A, ketamine pretreatment group K1，K2 and K3. Airway responsiveness were assessed using a whole body plethysm graphy RT-PCR was used to dectect the mRNA expression of NF--资B. NF--资B levels in bronchioles of all groups were measured by immunohistochemistry. Results:The increase of resistence of exhalation（Re） in group K1，K2 and K3 was significantly lower than that in group A with a dose of 50 -滋g／kg，100 -滋g／kg，200 -滋g／kg of acetylcholine（ACH）（P ＜ 0.01）. The decrease of Cldyn in group K1，K2 and K3 was significantly compared with group A with a dose of 50 -滋g／kg，100 -滋g／kg，200 -滋g／kg（P ＜ 0.01） of ACH. NF-кB P65 mRNA expression and NF-кB levels in asthma group was significantly higher than that of control group（P ＜ 0.05）, and that of K1，K2，K3 group significantly lower than that of asthma group（P ＜ 0.05）. Conclusion：Ketamine aerosol could effectively alleviate the airway hyperresponsiveness in allergic asthma rat.