Objective To explore the role of nuclear factor kappa B(NF-KB)in the pathogenesis of chronic obstructive pulmonary disease(COPD)and the therapeutic efects of glucocorticoid．Methods Twenty-four Wistar rats were randomly divided into three groups，ie．normal control，COPD model and prednisone preventive treatment group．Rat COPD model Was established by exposing the rats to cigarette smoke daily．Prednisone Was given through stomachal injection on altemate days．After COPD model Was set up，bronchoalveolar lavage(BAL)Was performed．Total cell counts and neutrophil counts in BALF were examined．Pathological changes of lung tissue Was observe0 by hematoxylin-eosin staining．The morphological indices of pulmonary emphysema(MLI，MAN and PAA)Was measured by a computerizedimage analyzer and compared in three groups．NF-KB expression in lung tissues were detected by immunohistochemistry assay．Rults Emphysema Was confirmed by three morphological indices in COPD model group compared to those of normal control group[MLI：(97.97±11.10)×10-6m vs (47．23±2．80)×10-6 m，MAN：(95.98±l4.89)×106 ／m vs (164.21±9．30)×106 ／m ，PAA：(64 ±5.7)％vs (44±2.7)％，Plt;0.01]．Total cell counts and neutrophil counts in BALF of COPD model group were significantly higher than those of control group[（5.76±0.29）×108/L vs （1.64±0.12）×108/L，（1.26±0.25）×108/L vs （0.099±0.065）×108/L，Plt;0.01]．After the preventive treatment with prednisone，MLI，MAN and PAA were significantly changed[（57.66±4.62）×10－6mvs （97.97±11.10）×10－6m，（111.40±16.92）×106个/m2 vs （95.98±14.89）×106个/m2，Plt;0.01；（58±6.1）% vs （64±5.7）%，Plt;0.05]，which indicated that airway inflammation and emphysematous injury in preventive treatm ent group were milder than those of COPD mode1．Total ceil counts and neutrophil countsin BALF were found in preventive treatment group as compared to those of COPD model[[（3.18±0.29）×108/L vs （5.76±0.29）×108/L，（0.57±0.12）×108/L vs （1.26±0.25）×108/L，Plt;0.01].The percentage of positive cells of NF-KB nuclear staining in bronchiolar epithelial ceils was significantly increased in the COPD group than that in the control group[（29.02±1.25）% vs （12.17±1.13）%，Plt;0.01]，but was significantly decreased in the preventive treatment group[(19.23±1.18)％vs (29.02±1.25)％，Plt;0．01]．Conclusions NF-KB may be responsible for the persistence and amplification of inflammation in COPD through neutrophil recruitment and activation．Prednisone may suppress airwayinflammation in COPD by inhibiting NF-KB．