Saussurea lappa (SL) and major compounds, sesquiterpene lactones, have been suggested to possess various biological effects, including anti-tumor, anti-ulcer, anti-inflammatory, anti-viral and cardiotonic activities. Therefore, the ethanol extract of Saussurea lappa root (ESL) is studied for the mechanism of its action in apoptotic pathway. ESL-treated cells manifested nuclear condensation, and fragmentation. ESL also triggered the mitochondrial apoptotic pathway, as indicated by a change in Bax/Bcl2 ratio and caspase-9/-3 activation. ESL induced p38 MAPK/JNK, p53, and ASK1 phosphorylation. ROS scavenger reversed ESL-induced apoptotic cell death via inhibition of caspase-3 and p38 MAPK/JNK phosphorylation. These results suggest that ESL induced apoptosis in HepG2 cells through the ROS-p38/JNK pathway.