Clubroot presents a serious threat to cultures of oilseed rape, especially if the share of this plant species in sowing structure is high. This is related to a long-lasting survival of pathogens resting spores in soil. The casual disease agent is Plasmodiophora brassicae Woronin – an obligatory, internal pathogen of Brassicae family which causes the formation of tumors on roots and hypocotyls. Plants with disease symptoms have a confined ability of nutrients’ and water uptake and this may cause considerable losses in quantity and quality of potential yield. Monitoring performed in cultivation areas and the information obtained from farmers allowed to confirm a threat of disease occurrence in several voivodeships. At the same time there is a serious danger of the infection spread to other regions of oilseed rape crops. Confining plant infection by clubroot pathogen may be obtained mainly by applying a correct crop rotation, and also by providing resistant varieties for cultivation. In the performed greenhouse experiment, reaction to the infection caused by P. brassicae of chosen winter oilseed rape cultivars was studied. The degree of plant infection was assessed at the growth phase of green bud. It was stated that cv. Mendel revealed significantly the lowest degree of infection, as compared to the other studied cultivars. The other tested varieties were infested in a differentiated degree, however these differences were mostly not confirmed statistically. The infection level was mainly dependent on places of soil derivation.