Abstract. A biochemical characterisation of blood was done in laboratory mouse lines originating from a heterogeneous outbred strain Fzt:DU which were selected for high body weight at 6 weeks of age (DU-6), for high total protein amount in the carcass (DU-6P) and for an index combining body weight and treadmill Performance (DU-6+TP) over 54 generations, respectively. The level of the following enzymes and Substrates were compared to the unselected control group (Fzt:DU): alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), lactate dehydrogenase (LDH), creatine kinase (CK), y-glutamyl-transpeptidase (GGTP), alkaline Phosphatase (AP), total cholesterol with its components LDL+VLDL- and HDL-cholesterol, triglyceride (Trig.), Creatinine (Crea.), lactate (Lac.) and glucose (Gluc). Concentration of some metabolic substances differed significantly in relation to the specific selection character. It is concluded, that selection indirectly diversified physiological State in the tested long-term selection lines in mice.