ABSTRACT. The dried roots of the plant Acanthopanax senticosus (AS) are used in traditional Oriental medicine and reportedly possess anti-inflammatory properties in vitro. However, whether AS has the same anti-inflammatory effect in vivo and the underlying mechanisms of this action remain unknown. In this study, we pretreated a mouse model of lipopolysaccharide-induced acute lung injury with AS and found that the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and neutrophils in bronchoalveolar lavage fluid were reduced and that inflammation in lung tissues was attenuated. To determine the mechanisms of these actions, we next assessed the effects of AS on the activation of the nuclear factor (NF)-kB pathway. We found that AS decreased the level of NF-kB and the DNA-binding activity of NF-kB. In summary, we found that AS attenuated the levels of TNF-α and IL-6 in the lung tissue of a mouse model of acute lung injury by inhibiting the NF-kB pathway.