Investigations were carried out in rearing station in Mrozowo on 92 bull calves. In the first year of life blood samples were collected every month and level of hemoglobin, red blood cells, white blood cells, hematocrits, total protein and its fractions, urea, nitrogen a-amine, AspAT, ALAT, AP, glucose, cholesterol and bilirubin were analysed. Usefulness for reproduction was defined by quantity and quality of semen obtained from bulls it 12-th month of life. Results were combined in correlative pairs and subjected to analysis of multiple regression. Occurence of great fluctuations of calculated correlation coeflicients (from positive to negative) and deficiency of longer periods with constant level of relationship suggest that examined blood indices are rather useless in prognosing semen quality.