Isoetin-4 -O-β-glucuronide, a new derivative of the rare 2 , 4 , 5 -trihydroxyflavone isoetin, has been isolated from Adonis aleppica, along with the known vitexin-2 -O-β-rhamnoside. These structures were established by means of DCI-NH 3 -mass spectral and NMR methods including full establishment of the CH-spin systems for both compounds. Furthermore, structural evidence is given for the presence of sinapoylglucose representing the first phenylpropanoid glycoside isolated from a member of the genus Adonis.