Immune-enzymatic ELISA protocol was used to verify the specificity of the polydonal antiserum (anti-Azospirillum brasilense N040) against Azospirillum brasknse strains WAS123 and WAS220.The optimal conditions for the serological characterization of Azospialum brasilense strains resulted from this experiment were, bacterial Count of 106 as it was the density that gave maximum optical density readings and the polyclonal antibodies dilution 104 as it gave full saturation for coating the cells. Detection 'of the survival of Azospirillum brasilense strains WAS123 and. WAS220 beside N040 as a reference strain, inoculated into carrier composed of fine peat (25%), vermiculite (75%) and CaCO3 (5%) using EUSA technique at five intervals (1, 7, 14, 30 and 60 days) after inoculation. All strains were capable to survive for 60 days. In a pot. experiment, the effect of Azospirillum brasilense strains WA5123 and WA5220 compared with Azospiallum brasilense Sp7 and N040 as reference strains on rice cv: Giza 172 at different growth periods 30, 60, 90 and 120 days from transplanting was studied. The initial density of the mass cultures of all bacterial strains used was 108 cells/ml. A good response of rice plant to inoculation with Azospirillum brathenseWAS220 was noticed. Inoculation had the highest effect on rice plant growth, followed by strain WAS123 and N040 compared with .the uninoculated control. Azospirillum brasilense Sp7 showed no effect on rice plants.