Two strains of the nitrogen-fixing cyanobacterium Anabaena , native to Indian paddy fields, displayed differential sensitivity to exposure to uranyl carbonate at neutral pH.Anabaena sp.strain PCC 7120 and Anabaena sp.strain L-31 displayed 50% reduction in survival (LD₅₀ dose),following 3h exposure to 75_μM and 200_μM uranyl carbonate, respectively. Uranium  responsive proteome alterations were visualized by 2D gel electrophoresis, followed by protein identification by MALDI-ToF mass spectrome- try.The two strains displayed significant differences in levels of proteins associated with photosynthesis, carbon metabolism, and oxidative stress alleviation,commensurate with their uraniumtolerance. Higher uranium tolerance of Anabaena sp. Strain L-31 could be attributed to sustained photosynthesis and carbon metabolism and superior oxidative stress defense, as compared to the uranium sensitive Anabaena sp. Strain PCC 7120.Significance: Uranium responsive proteome modulations in two nitrogen-fixing strains of Anabaena , native to Indian paddy fields, revealed that rapid adaptation to better oxidative stress management,and maintenance of metabolic and energy homeostasis underlies superior uranium tolerance of Anabaena sp. Strain L-31 compared to Anabaena sp. Strain PCC 7120