Evaluation of serum and liver alanine aminotransferase (ALT) and aspartate aminotransferase (AST) has been used to determine chick physiological and nutritional conditions. Thus, ALT and AST activities were determined in serum and liver chick tissues at seven days of age with specific BIOCLIN kits. Day-old male chicks, Ross, were fed with corn-soybean diets with 20 and 23% crude protein (CP) combined with 0, 50, 100, 150, 200, 250, 300 e 350 mEq/kg of electrolyte balance (EB). The experimental design was 8 x 2 factorial with eight levels of EB and two levels of CP. No significant interaction (P>0.05) was found between CP and EB levels for both serum enzymes. CP dietary content affected (P<0.01) ALT and AST serum enzymes activities: 20% CP resulted in the highest activities. No difference (P>0.05) was found in the liver activities of ALT. The 20% CP diets allowed the highest liver AST activities (P<0.05).  Also a significant EB and CP interaction (P<0.05) was observed for liver ALT activity. Although this, it was not possible to determine the better EB level for the best development. In conclusion the measurement of serum AST and ALT activities can be determined in order to evaluate the CP dietary level for  a better performance.