An ontogenetic study of parameters of anticoagulative and fibrinolytic system in the blood and urine was carried out on 56 healthy newborn infants at the age of 3 to 28 days. The obtained data and the performed correlation analysis of the coagulative system showed that there was acceleration of fibrinolysis in blood on the background of increased antiplasmatic activity of the blood, RKFM and the concentration of fibrinogen B in blood plasma; the inhibitory activity of the urine, fibrinolytic activity of the urine and the content of PDF in urine were reduced in comparison with the same parameters in older infants. Maximal statistically significant correlation dependences were established during the first week of life of newborn infants. The obtained data could be used as controls in studying various pathological states, connected with changes in coagulative and anticoagulative systems.