Abstract Root samples from 172 species of Aloe were surveyed by TLC and HPLC for the presence of anthraquinones and pre-anthraquinones. With the exception of the three species of the series Serrulatae , 1,8-Dihydroxyanthraquinones (chrysophanol and asphodelin) were detected in all the species sampled. Compounds derived through the 1-methyl-8-hydroxyanthraquinone pathway, i.e. aloesaponarin I, aloesaponarin II and laccaic acid d -methyl ester, together with their corresponding pre-anthraquinones were detected in 129 species. The results also show that isoeleutherol is a useful chemotaxonomic character for the series Saponarieae .