Background: numerous studies have shown that severity of respiratory distress syndrome may affect the endogenous cortisol secretion in preterm infants. Aim of the Work: assess the relationship between Cortisol level in umbilical cord in first and third day after delivery & Respiratory distress syndrome in preterm. Patients and Methods: a case control study that includes 90 preterm infant. Each included infant was submitted to history taking, complete clinical examination and laboratory investigations including complete blood count, arterial blood gases, level of cortisol in day one and day three. Results: in the present work, there was no significant difference between cases and controls as regard age, gender, weight, gestational age, as regards the serum cortisol levels in the studied groups,this study revealed that mean level of serum cortisol in 1stday of life among the three groups showed elevation and showed no significant statistical difference between the three groups (P-value = 0.107) Regarding mean level of serum cortisol in 3rd day of life showed high significant difference between the three groups (P-value = 0.001). group I (without RDS) marked lower than both groups II&III (with RDS), and comparison between group II and III regarding the same value, showed that group III had significant higher level than group II (P-value = 0.001). Conclusion: preterm infants respond to the stress at delivery and cortisol production continues in infants with RDS than those without RDS.