In this paper, the results of field studies of the effect of biological preparations Gliocladin-SC and Trichodermin-BL based on Trichoderma fungi on the yield of soybeans in the soil artificially contaminated with pathogenic fungi S.sclerotiorum (Lib.) de Bary. и F.sporotrichiella Bilai are presented. Two kinds of the contaminated soils were created by introducing the inoculum of two pathogens into the furrow during the sowing of 20 g seeds per 1 m lengthwise. In the natural conditions under the influence of the biological preparation Gliocladin-SC liquid form the yield of soybeans increased by 52,0% in comparison with the control; in the soil infected with Sclerotinia – by 62,8% and in the Fusarium-contaminated soil – by 64,5%. Application of the biopreparation Trichodermin-BL dry form increased the yield of soybeans under the condition of the natural infection by 23,6%, in the soil infected with Sclerotinia – by 47,1%, and in the soil, infected with Fusarium - by 49,5%, in comparison with the control. S.sclerotiorum and F.sporotrichiella contamination reduced soybean yield in comparison with natural conditions control in 3 times and in 2 times, respectively.