OBJECTIVE:To study the induction effect of paeoniflorin on the apoptosis of lung adenocarcinoma A549 cells. METHODS:MTT method was used to detect the viability of A549 cells 48 h after the cells were cultured with paeoniflorin of 0 (negative control),5,10,20 and 40μmol/L. 24 h after A549 cells were cultured with paeoniflorin at the above-mentioned concen-trations,enzyme-linked immunosorbent assay was employed to detect the viability of cysteinyl aspartate specific proteinase 3(Cas-pase-3),and Western blot to determine the protein expression of Bcl-xl,Bax,nuclear factor κB p65(NF-κB p65)and phosphory-lated nuclear factorκB p65(NF-κB pp65). RESULTS:Compared to the negative control group,A549 cells cultured with paeoniflo-rin of 5-40 μmol/L for 48 h showed lower cell viability;A549 cell cultured with paeoniflorin of 5-40 μmol/L for 24 h showed high-er activity of Caspase-3 and the expression of Bax;A549 cell cultured with paeoniflorin of 10-40 μmol/L for 24 h showed lower protein expression of Bcl-xl and NF-κB pp65. There were statistically difference(P<0.01 or P<0.05). CONCLUSIONS:Paeoni-florin induces the apoptosis of A549 cells by a mechanism which may be related to the activation of NF-κB signaling pathway and regulation related gene expression.