Investigation of a new collection of Ageratum corymbosum resulted in the isolation of three new flavonoids, 4'-hydroxy-5,6,7,3'-tetramethoxyflavanone, 5-hydroxy-6,7,2',3',4',5'-hexamethoxyflavone and 3'-hydroxy-5,6,7,2',4',5'-hexamethoxyflavone, named agecorynins E, F and G, respectively. Their structures were established by spectral methods and chemical transformations. 5-Hydroxy-7,8,2',3',4',5'-hexamethoxyflavone (isoagecorynin F), obtained from agehoustin B, is also reported.