The impact of breeding on winter wheat yields and the use of the generated yield potential in production were assessed. The results of trials of Research Centre for Cultivar Testing (COBORU) from 1966-2022, data from the Seed Inspection (IN) from 1986-2001 and Plant Health And Seed Inspection (PIORiN) from 2002-2023 regarding the varietal structure of seed production of winter wheat and production data on wheat yield in production were used according to Statistics Poland. To assess the effects of breeding, the method of changing the yield potential of varieties was used. In this method, we use indexes determining the yield-producing capacity of individual varieties in relation to the standard. Changes in yield trends in variety experiments and production were analyzed. The growing importance of the variety as a factor enabling further increase in yield and the effect of breeding on the increase in yield potential has been demonstrated despite limitations in the use of nitrogen fertilization and chemical plant protection products. The existing yield gap between trials and production, amounting to approximately 55%, indicates great opportunities to further increase yields in production through better use of the yield potential of varieties created by breeding.