A detailed chemical examination of the Indian senna leaves has been made. The ash has been analysed. An aqueous extract of the leaves has been found to contain a good amount of calcium salts. A petroleum ether extract yields senna wax consisting of free myricyl alcohol admixed with regular wax. Methods have been worked out for obtaining the flavonol and authraqui one group of compounds separately in the most convenient manner and in the best yield. The flavonol portion consists of iso-rhamnetin and kæmpferol in more or less equal quantities, whereas the anthraquinone portion contains mostly rhein along with small quantities of emodin.