Abstract： Objective To determine the effects of angiotensin Ⅱ (Ang Ⅱ) on NF-κB DNA binding activity in alveolar macrophage. Method Human alveolar macrophages were isolated and made homogeneous from alveo-lar lavage fluid, and cuhtured in DMEM. Alvcolar macrophages were treated with AugⅡ (10-6M) for 15 min, 30 min, 60 min and 120 min, respectively. Moreover, alveolar macmphages were pretreated with irbesartan (AngⅡ type 1 receptor blocker) for Ⅰ hour before stimulated with Angiotensin Ⅱ for Ⅰ hour. Electrophoretic gel mobility shift assay (EMSA) was used to detect NF-κB DNA binding activity. The protein expression of IκBα was examined by Western blot. Expressions of TNF-α and ICAM-1 mRNA were detected by using RT-PCR. Results EMSA re-vealed that there was a increase in up-regulation of NF-κB DNA binding activity after alveolar macrophages were treated with Ang Ⅱ for 15 rain and peaked at 60 min. Irbesartan treatment reduced DNA binding activity. Com-pared with control group, the protein expression of IκBα decreased in Ang Ⅱ treatment group(0.29±0.11, P= 0.013), and Irbesartan treatment significantly increased protein expression of IκBα(0.83±0.12, P=0.001). The expressions of TNF-α and ICAM-1 mRNA were up-regulated by AngⅡ in comparison with the control group (TNF-α:1.13±0.17 vs. 0.42±0.099; ICAM-1 0.55±0.08 vs. 0.16±0.050, P=0.003). Irbesartan inhibited the expressions of TNF-α (0.77±0.15 vs 1.13±0.17, P=0.02; ICAM-1(0.32±0.07 vs 0.55±0.08, P =0.001). Conclusions Ang Ⅱ is capable to stimulate NF-κB signal pathway in alveolar macrophages.