Septic shock is a frequent reason for admission on pediatric intensive care units. Interventions which can change morbidity and mortality of septic shock patients are of great interest. Steroid replacement in adults with severe sepsis and septic shock have been extensively studied. It was recently demonstrated that low dose steroid (< 300mg/ day) used for more than 5 days was associated with decreased mortality and lower requirement of vasoactive support in the adult population that had a low response to the ACTH test. However, this was not confirmed in the latest results from the CORTICUS study. Use of low dose hydrocortisone, or any other steroid has not been studied in critically ill children. Mortality associated with sepsis in children has decreased in the last decade and currently it is close to 10%, making it difficult to power a study able to show reduced mortality. Taking into account the results from previous studies reporting the high incidence of adrenal failure and its association to worse outcome, we have designed a clinical trial to evaluate the effect of low dose hydrocortisone in children with septic shock: Cortisol Replacement in Children with Sepsis Study.