Historically, for curing ailments, the inhabitants of Tibet, Ladakh and Lahaul-Spiti had practised shamanism that was prevalent in northern Asia under the name Ban. During the pre-Buddhist era, several forms of medical practice had existed in the trans-Himalayan region such as Ihaba (shaman) and Onpo (astrologer) and the prominent system of indigenous therapy developed in this desolate area was known as the Tibetan medical system, which has evolved on the basis of available bioresources, minerals and beliefs. Amchis being the practitioners of this ethno-medical system, have enjoyed high respect and social status among the trans-Himalayan Buddhist communities. With the spread of Buddhism in the trans-Himalayan region, Ayurveda began to influence the Tibetan medical system. There is ample indigenous medical knowledge with many traditional amchis, which has been inherited from one generation to the next by word of mouth, and not yet documented. The present study deals with the Tibetan Medical System and the ingredients used in preparing various ethno-medicines to cure several ailments by amchis inhabiting Ladakh and Lahaul-Spiti region of Indian trans-Himalaya. A total of 337 plant species, 38 species of animals and 6 minerals were documented during the survey period. Among 83 amchis interviewed, 36% had disciples or students, primarily their own sons and daughters. The study reflects that the Tibetan system of medicine is declining in the study area due to shift in socio-economic patterns and unwillingness of the younger generation to adopt amchi as a profession.