This study is a pioneering work offering a comprehensive analysis of the herbal medical tradition in rural Northern Thailand. The focus of the research is the description and classification of local disease concepts and the complex relationships between diseases, plants, drugs, and prescriptions. The work is based on extensive communication with local practitioners, clinical observations and local manuscripts. About 540 medicinal plants are identified in the appendix, together with their claimed medical properties. In addition, the book contains charters on the court medical tradition, and considers the prospects for the survival of traditional medicine in the face of competition from modern cosmopolitan medicine. The authors also provide extensive vocabularies, as well as indexes of disease terms and botanical names, including a Thai index of disease terms. There is a wealth of information for those interested in medicine botany and ethnopharmacology, while the history and anthropological aspects of the work will interest many other students of Southeast Asia.