Przytulski T., B. Bartoszewicz, H. Kamieniecki, A. Kaw~cki, A. Klemke, L. Niemyska, W. Belec: Genetic Resistance to Leukaemia in Black-and-White Cattle. Acta vet. Brno, 50, 1981: 61-66. Data obtained from 1312 Black-and-White cows of 75 bulls from different farms shows that bulls transmitted different levels of resistance or susceptibility to leukaemia to their daughters. It can be used in practice for early elimination of bulls which are genetically predisposed to leukaemia. The h 2 of leukaemia resistance was 0.13. Relationship between blood groups, transferrins, postalbumins, amylase, xCn, cc.,-Cn, {J-Cn (caseins) and {J-Lg phenotypes and leukaemia was also analyzed. In cows secreting xCn AA types there is a significantly lower incidence of leukaemia than in cows producing xCn BB or AB types. The frequency of Y2D'G'1' allele in cows with leukaemia was very high. The differences for the other phenotypes were not significant. Resistance, leukaemia, cattle, polymorphism.Leukaemia is a major animal disease. A significant percentage of domestic and wildlife animal