Plant sources of some traditional Chinese herbs may have changed over time. History records of herbal toxicity should be viewed critically when different plants might have been used under the same name in earlier eras. The current main source of the Chinese herb Mu Tong is Aristolochia manshuriensis. Examination of classical Chinese herbal literature revealed that until the mid 17th century the original source plants of Mu Tong had been several Akebia species. From the 17th century until the early 20th century Clematis species were the main source of Mu Tong. A manshuriensis has only been widely used since the 1950s. Renal failure due to ingestion of large doses of A. manshuriensis has been reported in China and other countries while no such toxicity has been recorded in traditional Chinese herbal texts. Documentation of traditional Chinese herbal literature should help to ensure the safe use of Chinese herbs.