Aim: Although, variations of normal immunoglobulin (Ig) levels in different gestational age and birth weight groups have been studied so far, data are still limited in newborns, especially in preterm infants. The aim of this study was to determine serum IgG and IgM levels in newborns in order to generate a reference standard for neonatal intensive care unit (NICU) and address the variations in preterm babies.Methods: This study was conducted from June 2012 to June 2013 in a level III NICU. A total of 300 newborn infants hospitalized within first 72h were included in the study. The quantification of serum IgG and IgM was performed by nephelometric method.Results: Both serum IgG and IgM levels were increased in correlation with increased gestational age and birth weight.Conclusion: The reference values of serum IgG and IgM levels should be further evaluated in larger series with the presented data in this article. In addition, preterm babies appear to have lower Ig levels thus carry the risk of relevant morbidity.