Asphyxia i a condition caused by lack of oxygen in tissues and organs. The basic pathogenic mechanisms of asphyxia are: 1)hypoxemia, 2) ischemia. The effects of perinatal asphyxia on the brain of a neonatal baby are critical in development of hypoxic-ischemic encephalopathy. The diagnosis of hypoxic-ischemic encephalopathy is based on clinical data including course of pregnancy and delivery (Apgar score) and especially on the neurological status of the newborn (consciousness, tonus, convulsions, reflexes, vegetative functions, etc.) and it can be confirmed by biochemical analysis and neurological examinations. The aim of this paper is to determine the importance of prenatal and perinatal risk factors for hypoxic-ischemic encephalopathy, as well as their effects on the development of neurological complications and further neurological problems. The research included 148 newborn infants born in the period from January 1, 1996 to January 1, 1999, with gestational age of 27 to 42 weeks, with hypoxic ischemic lesions of the central nervosus system. The control group included 58 children of the same age and the same gestation, with generalized hypotonia ("floppy infant") but without any signs of hypoxic ischemic lesions of the central nervous system. In the group of examined newborn infants with hypoxic ischemic lesions, from 149 children 1 (0.67%) died, 87 (53.89%) had normal findings, whereas the handicap was established in 61 (40.94%). Perinatal asphyxia affects the fetus and newborn infants not by individual factors, but with at least three or four associated factors. The disorders caused by asphyxia are in inverse proportion to the duration and intensity of hypoxic insults and the gestational age of the newborn. .