The present paper shows the results of laboratory investigations of seeds pretreatment impact on sweet corn seedlings development. Pretreatment was accomplished by biofungicides Gliocladin-SC and TrichoderminSC, based on Trichoderma fungi. It has been found out that the optimal consumption rate of the biopreparations was 1,0 l/t of seeds. The biometric characteristics of seedlings in comparison with the control increased by 18,5% - 23,6% and by 29,5% - 37,4%, after treatments with the biopreparations Gliocladin-SC and Trichodermin-SC, respectively. Biopreparations provide antifungal action against Fusarium verticillioides and F.graminearum, causative agents of the corn’s roots, cobs and seeds rot. Biologically active substances contained in biological preparations inhibit the development of pathogens and form sterile growth suppression zones on agar plates.