Plankton samples collected from the floodplain lakes (beels) and small wetlands (dobas or dubies) of Majuli, the largest river island of the world and a unique fluvial landform of the Brahmaputra river basin of northeast India, reveal 131 Rotifera species belonging to 33 genera and 17 families. Two Australasian (Australian & Asian), four Oriental, six Palaeotropical and one Holarctic species are biogeographically interesting elements; one species is a new record to India while several species are of regional interest. The rotifer fauna is predominantly tropical indicating high richness of cosmopolitan species and important contribution of tropicopolitan and pantropical species. Lecanidae > Lepadellidae are the most diverse families; Lecane Nitzsch > Lepadella Bory de St. Vincent > Trichocerca Lamarck are species-rich genera. The rotifers communities are characterized by several small-sized littoral-periphytic taxa, paucity of the Brachionidae in general and rare occurrence of species of Brachionus Pallas, Keratella Bory de St. Vincent, Filinia Bory de St. Vincent, Asplanchna Gosse and Polyarthra Ehrenberg in particular.