Nepal is the home of 59 indigenous nationalities distributed in four physiographic regions of Nepal viz. mountain (himalaya), hilly, inner terai and terai. Among them, the Lapcha people live in the Hilly region of Eastern Nepal in the Ilam district. On March 31, 2004, Nepal Federation of Indigenous Nationalities (NEFIN) has classified indigenous nationalities into five major categories i.e. endangered, highly marginalized, marginalized, disadvantaged and advanced group/s. Accordingly, Lapcha community is the endangered one. The total population of the community is 2589 (53 percent male and 47 percent female) distributed over 15 VDCs. They are rich in biodiversity although they are economically poor. Their indigenous knowledge over natural resources is remarkable. The Lapcha of Ilam district prefers to call themselves Lapcha rather than Lepcha as has been customary in Nepal. Such information is incorporated in chapter one as the introduction. Chapter two explains study area, methods of the data collection. The study was carried out in three VDCs of Ilam district namely, Shree Antu, Kolbong and Fikkal. They cover 33 percent of the total 499 households. The major objective of the study is to document indigenous knowledge on biodiversity of Lapcha community and further to make them aware of their knowledge and encourages them to preserve it for future generation and the humanity at large. Moreover, it also seeks to capacity building of Lapcha people through local research. Social research methods especially participant observation, semi-structure interview, focus group discussion and so on have been adopted for field study. Findings of the study were subjected to verify the information with local research partner/s as well as with key informant/s through a repeat visit. The chapter three describes the findings of the study. The study documented indigenous foods items; they included: 12 species of wild edible foods (Giththa, Bhyakur, Tarul); 11 species of unconventional food grains (Kaguni, Sama, Ghaiya, Junelo, Tite Fapar etc); 17 species of wild vegetables (Patle Sisnu, Rani Sag, Kali Nigro, Tite karela etc.); and 11 species of mushroom (Chyau) have been documented (Gobre, Jhhari, Bagale etc.). A list of scientific name and rong name (Lapcha language) with English name of plants has been provided in Annex four. In addition, 50 varieties of medicinal plant species have been recorded for 14 diseases such as diarrhea and dysentery, rheumatic pain, jaundice and so on. In the same way, indigenous knowledge in agriculture and livestock and in making natural dye has also been documented. Further, Lapcha people believed that they originated together with Choya Bans (Bamboo) on this earth. Seven different species of Bamboo have been documented, which are directly linked with Lapcha s livelihood and culture. Lapcha people make use of bird s behavior such as singing and calling to interpret nature and environment. They even alter their agricultural practices with reference to bird s singing and calling. They take it as a good or bad omen as per specific sound and its timing. Ten bird species have been recorded in this matter. Six case studies are presented to elucidate specific indigenous knowledge. The chapter four draws the conclusions and prescribes recommendations of the study. It is concluded that degradation of forests and practice of monoculture such as tea plantation accelerated in disappearing the indigenous foods items and medicinal plants. Chemical used for fertilizer, insecticide and pesticide further enhanced the same trends. Therefore, existing forest should be preserved to make enriched and revived the biodiversity. Likewise, organic farming has to be mandatory in the farming system. Indigenous knowledge can be converted into monitory benefits by establishing their intellectual property rights (IPR) in the long run. Documentation of these knowledge plays crucial role in this regards as Nepal has already entered into the WTO treaty. Therefore, it is recommended that this useful knowledge should be further researched and tested scientifically, which will be useful to all human beings in days to come. Finally, Lapcha community will be able to establish patent rights over their knowledge. This will definitely bring economic benefits to the community and the entire nation in future. Indigenous nationalities have to be made self-aware of their precious assets that have been passed down from generations. For this, local indigenous nationalities institution i.e. Rong Sejum Thi (Lapcah Uththan Manch) should play definitive role to create awareness among all Lapcha community. In addition, institutions working to uplift Nepalese indigenous nationalities like Nepal Federation of Indigenous Nationalities (NEFIN), National Foundation for Development of Indigenous Nationalities (NFDIN) and other agencies should develop strategies to work through concerned indigenous institution in these regards.