Biomass assessment of the macrophytic plant species were carried out at Poiroupat lake located in Imphal East district of Manipur. The present study reveals the presence of 30 aquatic macrophytes. The recorded aquatic macrophytes of the lake have been classified into four categories, viz. submerged (10%), rooted with floating leaves (16.7%), free floating (20%) and emergent (53.3%). In all the study sites, Ceratophyllum demersum recorded the maximum total biomass with values ranging from 24.52 (Site I) to 241.45 gm–2 (Site III). This was followed by Alternanthera philoxeroides with values ranging from 25.74 (Site II) to 139.77 gm–2 (Site II). This was successively followed by Utricularia flexuosa (14.12 to 110.45 gm–2), Ludwigia adscendens (14.09 to 89.32 gm–2), Nymphaea stellata (29.66 to 84.32 gm–2), Nelumbo nucifera (15.03 to 67.41 gm–2), Hydrilla verticillata (16.09 to 67.00 gm–2), Hygroryza aristata (30.95 to 62.52 gm–2), Ipomoea aquatica (4.54 to 58.31 gm–2), Nymphoides indicum (4.41 to 47.95 gm–2). Eichhornia crassipes recorded peak value of 26.54 gm–2. During the entire study period, the total biomass of all species (combined) ranged from 130.07 to 512.28 gm–2. The maximum biomass values were recorded during rainy season.