Background: Low selenium concentrations in the mother or her fetus can affect on infection risk, a major cause of preterm birth. Selenium status is also important in the group of hospitalized neonates and infants. Objective: This study aimed to measure cord blood selenium levels in full term and preterm neonates. Subjects and Methods: A total of 120 full and preterm neonates and their mothers included in this study. They were admitted to delivery room, Pediatric Department at Benha Teaching Hospital, Egypt. The study was conducted through the period from February 2020 to December 2020. They were subjected to full history taking, routine, physical examination and cord blood selenium was measured. Results: Full-term neonates had significantly higher GA, Wt., Lt and selenium levels than pre-term neonates. Also, there was no significant differences between full-term neonates and pre-term neonates regarding CRP, TLC and PLT. Also, selenium supplementation didn't show any significant effect on several clinical parameters as gestational age, weight, height, circumference, mother age, C-reactive protein, TLC and PLT among full-term neonates. On contrast, selenium supplementation showed a significant improved serum selenium level among preterm and full-term neonates. Conclusions: Full-term neonates had significantly higher selenium levels than pre-term neonates. Selenium concentrations are reduced in neonates, especially in those with lower gestational age and birth weight. Supplementation significantly affected serum selenium levels as compared to non- supplemented.