Cyanobacteria are microscopic organisms coming under the class Cyanophyceae. They are prokaryotic and diazo-trophic organisms that can perform both photosynthesis and nitrogen fixation. Cyanobacteria consists of about 2000 species coming under 150 genera and 5 orders. Among these species, they show variation in size and shape. For present study three sites were collected namely- Bunda (Site- 1st), Alipur (Site- 2nd) of Azamgarh district and Bhawanipur (Site-3rd) of Varanasi district. Only a few algae like Nostoc sp., Calothrix sp. and Anabaena sp. could survive during highly saline condition. Cyanobacteria identified to grow on “Usar” soils were unicellular species like Chroococcus, Aphanocapsa, Aphanothece, Gloeocapsa, Gloeothece and filamentous species like Microcoleus chthonoplastes, M. vaginatus, Nostoc calcicola, N. punctiforme, N. spongiaeforme, Calothrix brevissima, Anabaena ambigua, A. fertilissima, Scytonema sp., Cylindrospermum licheniforme, Aphanothece parietina, Aulosira fertilissima, Gloeocapsa stegophila, Phormidium sp, Oscillatoria subbrevis, Chroococcus macrococcus, spirullina sp., Anabenaopsis circularis, Lyngbya ceylanica and Scytonema, Calothrix and Tolypothrix. The major economic importance of Cyanobacteria is that they can be used as bio fertilizer in agriculture fields. The filamentous forms of Cyanobacteria we collected from the study area possess heterocyst, thus they can fix atmospheric nitrogen. This property of Cyanobacteria could be further studied and used for the preparation of bio fertilizers.