Method for selection of endophytic diazotropic isolates for use as nitrogen bio-fertilizer in rice cultivation is developed and standerdized. Ten endophytic diazotropic bacterial isolates were collected from roots of a wild rice species, Oryza rufipogon, from Sunderban area of West Bengal. These isolates were characterised on the basis of nitrogenage activity, siderophore & IAA production capacity. These isolates were also tested for contribution in yield attributing parameters in rice in pot culture. Based on these studies, 4 isolates were selected for field trials in coastal saline and red & laterite zones of West Bengal. In the trial 25% ( 20 – 22.5 kg) of recommended chemical nitrogen dose was deducted and supplemented by endophytic diazotropic bacteria application. Two isolates for each zones were selected on the basis of their contribution in 1000 grain weight and total yield in rice. These isolates are recommended for inclusion in INM package in rice cultivation.