Abstract:Five saikosaponins were isolated from the roots of Bupleurum scorzonerifolium Willd. A new saikosaponin was elucidated as the 3β, 16α, 23, 28-tetrahydroxy-oleana-ll, 13( 18)-dien-3-O- β-D-glucopyranosyl- ( 1 ~ 6 )- [ a-L-rhamnopyranosyl- ( 1 ~ 4 ) ] -β-D-glucopyranoside on the basis of spectral analysis and named as the saikosaponin s. The other four saikosaponins were determined as the saikosaponin a, saikosaponin c, saikosaponin bi and saikosaponin b2.