All the three soybean cultivars differed in symbiotic efficiency with used rhizobial strains, proving cultivar JS 335 superiority over the both cultivars DS 9712 and PK1042. Among all rhizobial treatments, strain ALSR12-GMR,VR gave significantly higher nodule numbers (52.25) than other strains with cultivar JS335. Cultivars JS335 and PK1042 expressed highest nitrogenase activity with strain ALSR12-SMR,VR whereas in cultivar DS9712, activity was recorded highest with strain USDA123-SMR,VR. Seed yield increased significantly in all three cultivars by treatment with phage resistant rhizobial strains; in cultivars JS335 and PK1042 with strain ALSR12-GMR,VR whereas in cultivar DS 9712 by strain USDA123-SMR,VR. Average increase in seed yield was about 8% more by inoculation of phage resistant mutants than their parental strains. Overall grain yield increase in soybean cultivars after inoculation was about 28% more than uninolulated control. These results indicated the existence of a relationship between phage resistance of the strains and selective host cultivars with regard to symbiotically effectiveness.