Abstract Aristoloside, a new companion aristolochicacidderivative isolated from stems of Aristolochia manshuriensis has been shown to be 6- O -β- d -glucopyranoside of aristolochic acid-D on chemical and physicochemical evidence. Three known acids, aristolochicacids I, IV (both as their corresponding methyl esters), and -D have also been characterized from stems of the plant.