The influence of different nitrogen source of varying concentrations on biomass production of green algae Scenedesmus was investigated. The result revealed that there was a significant difference among nitrogen sources in promoting algal biomass growth at lower concentrations of 5 and 10 mM. Nitrate was found to be a preferred form of nitrogen source and potassium (0.32 g/L) and sodium nitrates (0.28 g/L) performed better for biomass growth of Scenedesmus. Among the ammonical forms, urea (0.25 g/L) resulted in almost equal biomass as nitrates, making it an economical substitute for nitrogen source in large scale culturing of algae being commercially available. (C) 2012 Elsevier Ltd. All rights reserved.