The purpose of the studies conducted in the years 1996-1998 was to determine the quantitative and qualitative composition of bacterial and fungal communities in rhizosphere of soybean cultivated in monoculture and non-rhizosphere soil. Besides, the proportion of bacteria and fungi, which were distinguished by their antagonistic effect towards soil-borne pathogens was established. A microbiological analysis of lg of dry weight of soil from rhizosphere of soybean resulted in 3.21 x I ()6 to 8.70 x 106 bacterial colonies and from 70.51 x I 03 to 123.74 x 103 fungal colonies. In the case of non-rhizosphere soil, 3.50 x 106 to 4.75 x 10" bacterial colonies and 16.16 x 10' to 51.38 x 10' fungal colonies were obtained. Besides, soybean cultivation in monoculture had a negative effect on the number of antagonistic isolates of bacteria (Bacillus spp., Pseudomonas spp.) and fungi (Gliocladium spp., Penicillium spp., Trichoderma spp.). Smaller numbers of antagonistic bacteria and fungi in rhizosphere soil of soybean cultivated in monoculture as compared to non-rhizosphere soil, can prove little biological activity, which results in a worse phytosanitaty condition of the soil.