Background: Cortisol is one of the major hormones in stress condition to maintain the heamostasis in the body. The severity of disease is associated with cortisol level in the blood, there is dissociation between adrenocorticotropin (ACTH) and cortisol level in blood. This study aimed to evaluate serum cortisol level and adrenocorticotropin (ACTH) level in critically ill children. Methods: The present study was a single blinded randomized controlled interventional trail that was conducted in neonatal intensive care unit (NICU), pediatric department, Zagazig University children hospital in period between July 2017 to July 2018. 64 infants and children in the study. There were randomly divided into 2 groups. Group 1 included (24 males & 20 females) Group 2 included 20 healthy control subjects matched in age and sex. All patients were subjected to: measurement of blood pressure, heart rate, respiratory rate and temperature. Lab investigation included CBC, albumin, CRP and blood culture, basal cortisol and ACTH. Results: Mean ACTH at patients group was 21.7 ± 6.47 pg/ml and 11.3 ± 8.64 pg/ml in control group. Mean basal cortisol was 25.8 ± 4.62 ug/dl and 9.26 ± 1.95 ug/dl in group (1) and (2), respectively. Mean serum albumin was 3.16 ± 0.96 g/dl and 4.10 ± 0.45 g/dl in groups (1) and (2), respectively. There were a statistically significant difference between the patients' group and controls regarding serum cortisol and ACTH (p < /p>