Blue Green Algae which are also called as cyanobacteria are one of the most important nitrogen fixing photoautotrophs present on the eart`h since 3.5 billion years. They are known to be found in almost all photic habitats including water bodies, glaciers as well as all terrestrial ecosystems. Paddy fields represent one such habitat. Because of their autotrophic and diazotrophic nature they flourish in rice fields and known to sustain the fertility of this ecosystem. They very in their morphology. Some of them are unicellular while some are multicellular filamentous. An attempt has been made to document cyanobacteria from rice fields of Bhuvanagiri and Srimushnam Taluk, Cuddalore District, Tamilnadu, India. As many as 18 species of cyanobacteria were recorded from the study area. Order has been reported by nine of genera and 18 species. The genera Aphanocapsa, Aphanothece and Gloeocapsa were frequently reported.