Objective:To measure admission cortisol and adrenocorticotrophic hormone (ACTH) levels in children with meningococcal disease to try and determine the prevalence of adrenal insufficiency.Design:Prospective observational study.Setting:Pediatric departments of four hospitals in Merseyside, United Kingdom.Patients:Ninety-six children with meningococcal disease; 29 with hypotension, ten of whom died.Measurements and Main Results:Admission cortisol, ACTH, and proinflammatory cytokine levels were measured. Serial cortisol levels also were measured during the first 48 hrs.Significantly lower cortisol levels were found in those who died compared with survivors. Significantly higher ACTH levels also were found in those who died. However, no child had a cortisol level <5 μg/dL (<138 nmol/L) implying definite adrenal insufficiency. Three of 29 children with hypotension had plasma cortisol levels implying possible adrenal insufficiency (<18 μg/dL [<497 nmol/L]), but high ACTH levels were only found in one of those three.Cortisol levels decreased significantly after antibiotic treatment, unless steroid therapy was administered. ACTH levels did not correlate with cortisol or proinflammatory cytokine levels.Conclusions:Children with meningococcal disease have a wide range of initial plasma cortisol levels, with lower levels found in those who die. Many factors may affect cortisol levels, but adrenal insufficiency is probably uncommon.