Abstract: Objective To investigate the effects of a non-steroidal anti-infl ammatory drug（Valdecoxib）on human colon cancer HT-29 cell lines. Methods In vitro cultured HT-29 were divided into normal group(C), Valdecoxib group(V) and solvent control group(S). Apoptosis of HT-29 was analyzed by fl ow cytometry. The expression levels of COX-2, caspase-3, cleaved caspase-3, Bax, Bcl-2, p38 MAPK and p-p38 MAPK protein were detected by Western blot. Results Compared with normal group(C), cell apoptosis, the expression of cleaved caspase-3 and p-p38 MAPK and the ratio of Bax/Bcl-2 were signifi cantly increased in Valdecoxib group(V) (P<0.05). Valdecoxib interference could significantly promote cell apoptosis, the expression of cleaved caspase-3 and p-p38 MAPK, and the ratio of Bax/Bcl-2 in HT-29. Conclusion The inhibition effects of Valdecoxib on HT-29 apoptosis may be related with activating p38MAPK signal pathway.