A new aspect on delivery as "physiological stress" provides the possibility for assessing its influence in asphyxial newborns. Asphyxia is characterized by hypoxic ischemic damage of organs with subsequent damage due to reoxygenation and reperfusion. The aim of the study was to compare the activity of liver enzymatic systems of healthy newborns with asphyxial newborns. Reference values of the AST on the 1st day of life 0.80 +/- 0.12 microkat/l and on the 5th day of life 0.78 +/- 0.11 microkat/l, of the ALT on the 1st day of life 0.29 +/- 0.04 microkat/l and on the 5th day of life 0.54 +/- 0.21 microkat/l and of the quotient of DeRitis on the 1(st) day of life 3.35 +/- 0.6 and on the 5th day of life 2.14 +/- 0.22 were established. The quotient of DeRitis expresses better the influence of stress on healthy term newborns since isolated evaluation of liver enzymes and their dynamics, which is decreased on the 5th day of life shows stabilization of the baby and improvement of liver cell function in comparison with the 1st day of life. The authors found that delivery is considered to be a certain form of physiological stress.