As an attempt to search for bioactive natural products exerting antiinflammatory activity, we have isolated two saponins were isolated from the aerial portion of Pleurospermum kamtschaticum (Umbelliferae) by nitrite assay activity-directed chromatographic fractionation. They were identified as saikogenin F 3-O-{beta-D-glucopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->3)]-beta-D-fucopyranoside} (buddlejasaponin IV, 1) and 3beta,16beta,23,28-tetrahydroxy-11alpha-methoxyolean-12-ene 3-O-{beta-D-glucopyranosyl(1-->2)-[beta-D-glucopyranosyl(1-->3)]-beta-D-fucopyranoside} (buddlejasaponin IVa, 2). Compound 1 significantly inhibited nitric oxide (NO) production, and it also significantly decreased prostaglandin E2 (PGE2) and tumor necrosis factor-alpha (TNF-alpha) release in the lipopolysaccharide (LPS)-activated macrophage Raw 264.7 cells whereas compound 2 was much less active. Saikogenin A (3) and -H (4) were obtained by hydrolyzing 1 and 2. Although these sapogenin showed strong NO inhibition, these effects were caused by the cytotoxic effect on Raw 264.7 cells. These results supported the notion that buddlejasaponin IV is a major inhibitors of NO, PGE2 and TNF-alpha production in P. kamtschaticum.