In the three-year experiment (2006–2008) the impact of three different spring cereals (wheat, barley, oat) and their two- and three-component mixtures were tested. The studies were carried out at two sites. The impact of mixtures on disease reduction, pests occurrence and yield height compared with pure stands were evaluated. Observations on powdery mildew occurrence during the vegetation season were done every 7–10 days. In order to compare the disease occurrence levels on different cultivars in pure stands and on their mixtures the Area Under Disease Progress Curve (AUDPC) was evaluated. Based on the AUDPC values, the reduction of powdery mildew occurring in the mixtures due to epidemiological and ecological factors functioning in mixed stands were also evaluated. The occurrence of these pests: Aphidodea, Oulema spp., Agromyzidae, in spring cereals was evaluated twice in the vegetation season. Based on the obtained results, it can be stated that winter barley cultivar mixtures do reduce the powdery mildew incidence and pest occurrence compared to pure stands. Also from the results, it can be stated that winter barley cultivar mixtures can constitute an alternative way of growing winter barley, especially in low-input and ecological agriculture. The aim of the studies was to evaluate the yield through growing spring cereal mixtures. Positive effects (up to 8 dt/ha yield increase in mixtures compared to pure stands) were observed. On the base of obtained results it can be stated that spring cereal mixtures can constitute an alternative way of growing, especially in low-input and ecological agriculture.