A novel 8,14-dihydromorphinandienone alkaloid was isolated from the dried leaves of Cissampelos sympodialis. Spectroscopic analysis established its structure as (+)-(9 beta,13 beta,14 alpha)-5,6-didehydro-4-hydroxy-3,6-dimethoxy-17-methylmorphinan-7-one, to which we have given the name, milonine.