Three new aconitine-type C19-diterpenoid alkaloids, richardsonines A-C (1-3), were isolated from the roots of Aconitum richardsonianum Lauener, together with seventeen known compounds (4-20). Their structures were elucidated by extensive spectroscopic analysis, and the absolute stereochemistry of 1 was confirmed by X-ray crystallography. Compounds 2, 5, 8 and 9 were rare C19-diterpenoid alkaloids bearing an OH group at C-16. Isolated compounds were evaluated for inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated neuroinflammatory responses in BV-2 microglial cells. Compounds 3 and 7 showed weak anti-neuroinflammatory effects with inhibition rates of 35.32 & PLUSMN; 2.29% and 39.94 & PLUSMN; 2.50%, respectively, at a con-centration of 100 mu M.