Screening of extracts from ALOE VERA revealed the presence of endogenous arachidonic acid, a potential precursor for the prostanoids synthesis. The presence of endogenous cyclooxygenase, in the plant extracts, was established by radiometric assay. Relatively high proportions of PGE (2) and TXB (2) and low proportions of other prostaglandins were identified in the plant extract when incubated with [ (14)C]-arachidonic acid. Other lipids present in this plant were examined and a high percentage of phosphatidylcholine and cholesterol was established. Possible importance of prostaglandins formed endogenously by the plant is discussed.