Saussureae Radix, the dried root of Saussurea lappa Clarke, has traditionally used for alleviating pain in abdominal distention and tenesmus, indigestion with anorexia, dysentery, nausea, and vomiting. Here we observed that methanol extracts of Saussurea Radix inhibited CDK2 activities in vitro. This inhibitory compound was isolated and identified as dehydrocostuslactone, one of the major constituents of Saussurea Radix. It is well known that dehydrocostuslactone induces apoptotic cell death. In this study, we also showed that dehydrocosruslactone inhibited cellular Rb phosphorylation and blocked cell growth at the concentration below $12;{mu}g/ml$ at which apoptotic cell death was not observed. Taken together, these results indicated that dehydrocostuslactone showed its anti-proliferative effects through the inhibition of CDK2 activity as well as the induction of apoptotic cell death.