Chemical investigations on the leaves of A. berhana Reynolds, A.rnrivae Oaker, A. megalacantha Baker and A. pulcherdma ined. resultedrnin the isolation of a total of nine compounds, the structures of whichrnwere established by spectroscopic means as well as chemical degradationrnto known compounds and compaidLson, in some cases, with authenticrnsamples. Chrysophanol and P -Sitosterol were isolated from all fourrnspecies. Furthermore, A. berhana afforded a novel pre-anthraquinonern(tentatively given the trivial name berhanone), protocatechuic acidrn(a biologically important aromatic acid rare from a natural source),rnbarbaloin (the major active constituent of the officially recognisedrncommercial aloes responsible for the- use of the plant as purgative)rnand aloe-emodin. A. rivae and A. megalacantha yielded aloe-emodin,rnberhanone, barbaloin and aloinoside (a constituent of the commerciallyrnimportant Cape and Socotrine aloes). A. pulcherima afforded nataloinrn(major constituent of the commercial Natal aloes) add 7-hydroxybarbaloinrn(the characteristic substance of the commercially important Curacao aloesrnin the European Pharmacopoeia).rnA further comparative chemical screening on the presence of the commerciallyrnimportant compound, barbaloin, in the loaves of some Aloe species byrnmeans of HPLC and TLC analyses revealed that this glucoside is the majorrnconstituent of A, berhana Reynolds, A. rivae Baker, A. megalacantha Baker,rnA* calidophylla Reynolds, /. secundiflore Engler, A. mcloughlinii Christian,rnand A. otalensis Baker, Barbaloin was, however, not detected in thernleaves of A. pulcherimn.