Abstract:The crude drugs of Rhizoma Arisaematis and Pinelliae are different in medical effect,butvery similar in appearance.Our studies have shown that they can be distinguished by the diffe-rences in their microscopic structures between mucilage cavity and secretory cell with brown contents,by the avilability of clustered calcium oxalate crystals and by the shape of calcium oxalate raphidesin single or multi-bundle,etc.