Phytoplanktons are microscopic free floating animals which play a vital role in aquatic ecosystem. Phytoplanktons are highly sensitive to environmental variation, as a result change in abudance, species diversity or community composition can provide important indication of environmental health. Phytoplankton diversity is controlled by seasonal variation. In the present paper an extensive review of the literature available on seasonal variation of Phytoplanktons in lotic water of India have been made which is a long felt necessity in this field.