Saussurea Radix, the dried roots of Saussurea lappa Clark (Compositae), has been used in oriental traditional medicine for aromatic stomachic. Present study was carried out for the anticancer effect of Saussurea Radix. Bioassay-directed fractionation of Saussurea Radix led to the isolation of two sesquiterpenes, dehydrocostuslactone (1) and costunolide (2). The structures of 1 and 2 were elucidated by spectral methods (MS, IR, $^1$H and $^{13}$C NMR). These compounds showed a potent cell proliferation activity against human breast cancer cell MCF-7 and MDA-MB-453.