A new flavanone, 4',5,7-trihydroxy-6,8-di-(2-hydroxy-3-methylbut-3-enyl)- flavanone, was isolated from the aerial parts of Derris trifoliate, together with eleven known compounds: rotenone, tephrosin, 12a-hydroxyrotenone, deguelin, 6a,12a-dehydro-rotenone, dehydrodeguelin, 7a-O-methyldeguelol,