Titel of the paper: <b>Proteolytic activities of lysosomal enzymes in dairy cattle. I. Variation of lysosomal enzymes in dairy cattle</b><br> There are no references to be found in the literature dealing with genetic aspects of lysosomal enzyme activities m blood of dairy cows, The used amino peptidases are connected to the proteolysis. 1011 investigated cows showed Variation coefficients of ≈50%, higher than in milk traits In simultaneous samples it reduces to 20–30% similar to daily milk samples The heritability coefficients h<sup>2</sup> = 0,10–0,20 is approximately between fertility traits and milk traits The investigation of lysosomal enzyme activities might be limited to plasma. No additional information could be gained using the leukocytes. Changing activities of enzymes in plasma are aqually directed to the milk performance. It may be concluded that the trait spectrum might be reduced to DP-IV, AGR, ALA, AGLD and EL as well especially to protein yield of milk.