140 dead fetuses and neonates of 21-40 week gestation were studied with morphometric study of hemopoietic activity of hepatic parenchyma. The correlation-regression analysis has established that hemopoietic activity of the liver in premature neonates reduces exponentially with duration of their extrauterine life. First, there was hyperplasia of hemopoietic tissue of the liver, its involution was observed 19 hours after birth, on the average, reaching maximum to the end of early neonatal period. Basing on the difference of gestation age estimated by the degree of hemopoietic activity of hepatic parenchyma and neonatal mass, a regression model of determination of neonatal period of life of premature babies was developed. The results of the study can be used for practical application in forensic medical examination of perinatal death cases.