The antiplasmodial activity and toxicity data of 34 Aloe species and their main constituents were determined. A number of the methanol extracts possessed antimalarial activity where 50% of the parasite growth was inhibited (IC50 value) by 32 to 77μg ml-1 of the extract. The chemical common to the most active species is the anthrone C-glucoside homonataloin which inhibited the chloroquine-resistant Plasmodium falciparum strain with an IC50 value of 13.46 ± 1.36μg ml-1. Homonataloin was a more potent inhibitor of parasite growth than aloin (IC50 value of 107.20 ± 4.14μg ml-1). The Aloe extracts tested did not exhibit any toxicity towards transformed human kidney epithelium cells at the concentrations (0.5-50μg ml-1) used in the antimalarial assay.