Carnitine plays an essential role in the transfer of long chain fatty acids across the inner mitochondria membrane specially in the early neonatal period oxidation. The aim of our study was to measure serum level of L-carnitine in healthy (Pre and full term) and septic neonates to study the effect of gestational age, birth weight and stressful conditions as sepsis on serum level of L-carnitine. This study was conducted on 30 neonates. They were divided into 3 groups, group 1, 10 healthy preterm neonates with a mean gestational age 33.60 wk + 1.43, group 2, 10 healthy full term neonates with a mean gestational age 38.60 wk + 1.07 and group 3, 10 septic neonates with a mean gestational age 36.10 wk + 3.25. The mean serum L-carnitine level in the three groups it was 37.39 mol/L + 3.37, 26.88 mol/L + 2.32 and 19.10 mol/L + 2.72 respectively. There was significant negative correlation between serum level of L-carnitine and both gestational age and birth weight in groups (1 & 2). There was a significant decrease of serum L-carnitine level in septic neonates compared to its level in healthy neonates.