In the global farming the soy takes one of the first places among the crops on the scale of production. Today the cultivar range has greatly enriched and improved gross grain soybeans, but the realization of the genetic potential of modern cultivars is relatively low. Aim. To study the inoculants influence on the plants development, soybean-rhizobia symbiotic systems formation, morbidity and productivity of modern soybean cultivars belonging to the different maturity groups. Methods. Microbiological, gas-chromatographic, statistical, the method of field research. Results. The positive effect of seeds treatment by mono- and complex inoculants on plant development, symbiotic system formations, disease manifestation reduction and productivity of soybean cultivars Medea, Moravia, Madison belonging to different groups of ripeness has been established. The stimulating effect of these inoculants on germination, growth, development and nitrogenase activity of nodulation apparatus and crop of soybean cultivars has been shown. Conclusions. Inoculation by nitrogen-fixing and phosphatemobilizing bacteria formulations has helped to reduce the morbidity of plants with bacteriosis and mycosis, and promoted the increasing of grain yield in 18,4 -120,0% compared with the control. The largest increase in yield has been obtained by complex inoculation of early ripening cultivar Medea.