To get insight in the endocrine and metabolic responses in children with meningococcal sepsis 26 children were studied the first 48 h after admission. On admission there was a significant difference in cortisol/ACTH levels between nonsurvivors (n = 8) and survivors (n = 18). Nonsurvivors showed an inadequate cortisol stress response in combination to very high ACTH levels, whereas survivors showed a normal stress response with significantly higher cortisol levels (0.62 vs. 0.89 micromol/L) in combination with moderately increased ACTH levels (1234 vs. 231 ng/L). Furthermore, there was a significant difference between nonsurvivors and survivors regarding pediatric risk of mortality score (31 vs. 17), TSH (0.97 vs. 0.29 mE/L), T3 (0.53 vs. 0.38 nmol/L), reverse T3 (rT3) (0.75 vs. 1.44 nmol/L), C-reactive protein (34 vs. 78 mg/L), nonesterified fatty acids (0.32 vs. 0.95 mmol/L), and lactate (7.3 vs. 3.2 mmol/L). In those who survived, the most important changes within 48 h were seen in a normalization of cortisol and ACTH levels, but without a circadian rhythm; a decrease of rT3 and an increase in the T3/rT3 ratio; and a decrease in the levels of the nonesterified free fatty acids and an unaltered high urinary nitrogen excretion. At this moment, it is yet unknown whether the hormonal abnormalities are determining factors in the outcome of acute meningococcal sepsis or merely represent secondary effects. Understanding the metabolic and endocrine alterations is required to design possible therapeutic approaches. The striking difference between nonsurvivors and survivors calls for reconsideration of corticosteroid treatment in children with meningococcal sepsis.