Abstract: 【Abstract】 Objective To study the influence of arsenic trioxide combined with human tumor necrosis factor related apoptosis inducing ligand (TRAIL) on the apoptosis and the expression of NF-κB of human non-small-cell lung cancer cell line. Methods The proliferation of human non-small-cell lung cancer cell line A549 cultured in vitro were treated by As2O3, TRAIL alone and combined. The cell proliferation was detected by the assay of MTT, flow cytometry with PI stain was used to detect the apoptosis rate, NF-κB mRNA level of A549 cells were detected by RT-PCR. The expression of NF-κB protein were detected by Western blot. The activity of NF-κB was measured by ELISA. Results Compared with As2O3 alone, As2O3 combined with TRAIL could increase the inhibition and apoptosis ratio significantly (P<0.05). The expression of NF-κB in combined group was obviously less than that in As2O3 alone and control; the activity of NF-κB was inhibited by combined groups. The NF-κB mRNA and protein expression and the activity of NF-κB were separately negative related with the apoptosis ratio (P<0.05). Conclusion As2O3 can enhance TRAIL inducing of human lung cancer cell lines A549 apoptosis by inhibition of NF-κB signaling pathway.