The aim of our work was to research the ability of Bradyrhizobium japonicum strains with different growth rates to produce phytohormonal substances and to assess their influence on the host-plant. Microbiological, serological, vegetation experiment, statistical methods were used. It has been established that active strains of nodule bacteria are capable of producing phytohormonal substances of auxin and cytokinin nature. Differences between the strains were determined by the level of phytohormones synthesis: A slow-growing B. japonicum strain 46 produces more auxins (48.4 mcg / g absolutely dry biomass tо 34.2 mcg / g), whereas the intensive-growing B. japonicum strain КВ11 predominates in cytokinins amount (835.3 mcg / g ADB tо 328.5 mcg / g). It was established that not only bacteria strains, but also the products of their metabolism are capable of causing quantitative changes in the composition of nodule populations of rhizobia and positively influence on formation and functioning of the soybean symbiotic systems. Binary inoculation of soybean with strains of B. japonicum 46 and KB11 proved to be more effective in influencing on plants than monoinoculation by each strain separately. Against the background of soil population of rhizobia, seed treatment with metabolites of two strains in the form of filtered culture fluids provided an increase in the aboveground phytomass of soybean similar to living cells of these microorganisms (on 16.9% compared to the control).