EN
During the last years there are papers on bovine leukosis published in Poland (28, 17, 27, 2, 9, 10, 5, 26, 1, 11, 13). These publications have been concerned mainly with studies on reliable diagnostic methods, with special regard to haematological examination which is the most useful in a clinical diagnosis. However, since aleukaemic forms of leukosis and leukocytoses of other aetiology can occur (8, 3, 4, 22, 24, 25, 19, 20, 12, 18, 21, 5), this method does not guarantee an absolute certainty. Therefore, to obtain undoubtful results, the diagnosis of leukosis should always be based upon haematological and histological examinations. The following paper presents the results of pathological examinations of cattle suspected of leukosis clinically or post mortem.