Abstract: In order to look for lower toxic and strongly active compounds, the structure of sesquiterpene lactones from Elephantopus scaber was modified. Deoxyelephantopin and scabertopin were isolated from the whole plant of Elephantopus scaber and hydrogenated and epoxidated. Five sesquiterpenoide derivatives were prepared and their structures were identified by IR, NMR and MS spectra analysis. Four sesquiterpenoides are new compounds. Part of the compounds show definite antitumor activity.