Analysis of the aerial parts of two Allagopappus species has yielded several known compounds and new sesquiterpene lactones related to the ineupatorolides: compound 3 was obtained from A. viscosissimus, compound 12 from A. dichotomus ssp. latifolius, and compounds 20,21, and a mixture of 22 and 23 from A. dichotomus ssp. dichotomus. New thymol derivatives were isolated from A. dichotomus ssp. latifolius [5] and A. dichotomus ssp. dichotomus [5 and 16]. The structures of these new natural products were established by spectroscopy, and the chemotaxonomy of the genus as a whole is briefly discussed.