Majuli, one of the largest inhabited river islands in the world, is under serious threat due to large-scale bank erosion by the Brahmaputra River. There is urgent need to preserve this socio-culturally rich island of over 0.2 million people. Erosions have been shrinking its landmass significantly and thereby causing enormous pressure on its ecosystem. Through this study, an attempt has been made to assess the effect of flood and erosion on the island, its nature, habitats and eco-system. Survey maps and satellite data are considered as major inputs to this study.