Desmid diversity is an important criterion for evaluating the suitability of water for irrigation and drinking purposes. Desmid population of Bhadra reservoir was studied for a period of two years from July 1998 to June 2000. In the present study, a total of 9 genera and 46 species of desmids were recorded and the important genera include Cosmarium with 25 species, Closterium with 3 species, Euastrum (2 species), Staurastrum (11 species), Micrasterias (1species), Desmidium (1 species), Arthrodesmus (1 species), Staurodesmus (1species) and Xanthidium (1 species). With regard to their seasonal occurrence, they were found to be more during summer (58174o/l) and low during rainy season (42016 o/l).