Objectives: to determine the relationship between the initial nucleated red blood cells (nRBC) count during the first 12 hours after birth and inborn infection in neonates. Materials and methods:The retrospective study comprised of 306 neonates born in the Department of Perinatology of the I Chair of Gynaecology and Obstetrics in Lodz, Poland, in the years 2002-2007, among whom the nucleated red blood cells count were calculated within the first 12 hours after birth. Two categories of nRBC count: the normal and the elevated value, were statistically elaborated by a Mann-Whitney test and a chi-square test with two clinical outcome categories: the presence and the absence of inborn infection in the analyzed neonates. Statistical significance was indicated by p value lower than 0,05. Results: Among 306 newborns, there were 127 mature neonates (41.5%) and 179 prematures (58.5%). The mean of the initial nRBC count in the analyzed newborn population was 40,15. The mean of the nRBC count in the infected neonates was three times higher (52.56) than the mean of the nRBC count in newborns without inborn infection (16.76) - (p=0.00001). Inborn neonatal infection concerned a vast majority of cases with an elevated value of the nRBC count (86.4%), but in 13.6%, inborn infection was not observed. Among the cases with a normal nRBC count, the presence and the absence of inborn infection was diagnosed in about 50% of the analyzed babies (50.83% vs 49.17%). The elevated value of the nRBC count in infected neonates concerned mainly premature babies, rather than mature neonates, and similarly in neonates with a lower Apgar score than in babies born in good condition. Conclusions: 1. The positive association between elevated initial nucleated red blood cells count after birth and inborn infection in newborns has been revealed. 2. An elevated nucleated red blood cells count may be an auxiliary, early indicator for inborn infection in neonates. 3. Prematurity and perinatal asphyxia favour the elevation of a nucleated red blood cells count in cases with inborn infection.