Abstract: The aim of this research was to study the effect of intramuscular supplementation of 5000 IU of vitamin A three times per week for 28th days on the serum levels of interleukins 4 and 5 and on the incidence of chronic lung disease in premature and low birth weight infants. This study was conducted on 30 premature and low birth weight infants admitted to Neonatal Intensive Care Unit (NICU) of the Pediatric Hospital of Ain Shams University. They were 14 males and 16 females with a mean gestational age of 31.88±2.17 weeks and a mean birth weight of 1.723±0.372 kg. Critically ill newborns were excluded from the study. The patients included in this study were randomly divided into 2 groups; Group 1 comprised 16 premature infants who received vitamin A supplementation in a dose of 5000 IU intramuscular (IM) 3 times per week starting from the 1st day of admission till the 28th day and Group 2 comprised 14 premature infants who did not receive vitamin A supplementation. Ten apparently healthy full-term newborns appropriate for gestational age served as controls. All premature and full-term infants included in the study were subjected at birth to measurement of serum levels of retinol, IL-4 and IL-5. On 28th day, levels of serum retinol, IL-4 and IL-5 were reassessed for the premature infants only. The mean serum levels of retinol, IL-4 and IL-5 were significantly lower in both group 1 and 2 infants at birth compared to those of controls. After vitamin A supplementation to group 1 infants, the mean serum levels of retinol, IL-4 and IL-5 as well as the rates of change of serum retinol, IL-4 and IL-5 levels were significantly higher in group 1 infants compared to those of group 2 after 28th days of life. However, the mean levels of serum retinol in group 1 infants was still significantly lower in group 1 infants compared to controls. Further, the serum IL-4 and IL-5 levels were significantly correlated positively with the serum retinol levels on 28th day after birth in group 1 infants. The preterm infants of group 1 had significantly lower incidence of chronic lung disease than infants of group 2. Meanwhile, gestational age, birth weight, the mean serum levels of retinol, IL-4 and IL-5 as well as the mean rate of change of serum retinol were significantly lower in infants who developed CLD on 28th day. Finally, we can come to the conclusion that vitamin A supplementation to premature and low birth weight infants appears to increase serum levels of IL-4 and IL-5 and may be behind the decrease in the incidence of chronic lung disease. Thus, it is recommended to supplement all premature and low birth weight infants with vitamin A.