Abstract: Objective To investigate the possible signal pathway of multi-drug resistant P-glycoprotein（P-gp）expression induced by cyclooxygenase-2（COX-2）in hunman gastric adenocarcinoma cell line SGC-7901 stimulating with pacliaxel（TAX）. Methods The effects of TAX on SGC-7901 cells growth was assessed by MTT assay，and so did the effects of COX-2 selective inhibitor NS-398 and nuclear factor-κB （NF-κB） pathway inhibitor pyrrolidine dithiocarbamate（PDTC）.The effect of a dose-ranging TAX and the change of combining NS-398 or PDTC with TAX on the COX-2，p65 and P-gp expression were detected by Western blotting. Results TAX，NS-398 and PDTC all had the effect of cellular toxicity on SGC-7901 cell line growth in a dose-dependent manner. When the dose of TAX（0.1，0.3，0.5μmol／L） increased，the expression of COX-2，p65 and P-gp showed rising trend in SGC-7901 cell line. And the expression of three proteins could decrease with the increase of dose and extension of time after combined with NS-398（5，10μmol／L）. When combined with PDTC（0.2μmol／L），the expression of p65 and P-gp decreased significantly. Conclusion COX-2 may induce the expression of P-gp in SGC-7901 cell line via NF-κB pathway with the stimulation of TAX.