Experiments were conducted at the Seed Laboratory, Department of Agronomy, Poznań University of Life Sciences, Poland. Seeds colonised by Fusarium ssp. fungi to different extent and selected Trichoderma ssp. strains (T1 - T. atroviride, T2 - T. atroviride, T3 - T. harzianum, T4 - T. harzianum, T5 - T. harzianum) were investigated. There were three independent series of bivariate analyses with 4 replicates. The results showed that the infestation with fungi of the Fusarium ssp. genus significantly affected the quality of seeds. The lowest sowing value parameters were observed in the seeds which were most colonised by the fungi (38%). The Trichoderma ssp. strains significantly modified the value and vigour of winter wheat seeds. When strain T2 - T. atroviride was applied, the quality of winter wheat seeds was higher. They were characterised by higher germination energy and capacity, greater vigour (expressed by means of the seedling growth test and the seedling growth rate test), greater fresh weight and longer radicles.