An ethnobotanical survey was carried out to collect information on the use of medicinal plants by the Lisu people who live in the mountainous areas of the Nujiang Canyon (Salween River Valley) in Nujiang Prefecture, northwestern Yunnan Province, China. A total of 52 medicinal plants, belonging to 32 families, were reported as being used locally for the treatment of human ailments. The scientific and Lisu names, parts used, and preparation of the plants are presented. Most of these species are wild (80%), while others are domesticated (8%) or semi-cultivated (12%). Among the 52 species, 11 species (21.2%) were reported as rare and 16 were widely commercialized in the region. Over-exploitation and deforestation are the main causes for the depletion of medicinal plants in this area. The Lisu people still mostly depend on medicinal plants for their health care. The loss and endangered status of these plants will, to a certain extent, impede their existing health care system; conservation and sustainable harvest of medicinal plants in the area are urgently needed.