A field experiment was conducted in a clayey soil to study the effect of inoculation with five Bradyrhizobium japonica strains namely, (USDA110, USDA HH303, UK 3407, USDA 118 and ARC500) to four soybean cultivars differing markedly in morphological traits (Clark, Crawford, Giza35 and Mc-call) on nodulation, growth, yield and yield components. Results revealed that the most effective symbiosis (leading to nitrogen fixation and good seed and straw yields and protein content) was achieved by careful selection of the appropriate strain for each cultivar. Strain USD A110 was the most efficient strain in N_2-­fixation and in increasing seed and straw yields on each cultivar followed by USDA HH303, USDA 118, ARC 500 and UK 3407strains, respectively.The tested soybean cultivars were differed in their response to inoculation. The highest responses were reported by Clark followed by Giza 35, Crawford and Mc-call cultivars, respectively. Generally, soybean inoculation with any strain of B. japonicum gave high responses in all tested parameters compared to those due to uninoculated plants and amended with the recommended dose of nitrogen fertilizer.