Three new sesquiterpene lactones were isolated from the aerial parts of Perymenium grande Hemsi (Asteraceae), collected around Rincón de la Vieja Volcano, Costa Rica. In addition to the three new lactibes 1, 3 and 5; were isolated the additional five known sesquiterpene lactones. The separations were performed with chromatographic techniques and the structures were elucidated by one- and two-dimensional nuclear magnetic resonance techniques.
