Glucocorticoids have been used therapeutically in critical illness for at least 50 years. This chapter considers the rationale for the use of glucocorticoids in sepsis and septic shock, acute respiratory distress syndrome (ARDS), pneumonia, postextubation stridor, spinal cord injury, meningitis and cerebral oedema. Synthetic glucocorticoids are administered most commonly to the intensive care unit (ICU) population intravenously, although they may be given by the oral, rectal, intramuscular, inhalational, intra-articular or topical routes. Glucocorticoids are used in many pulmonary disorders seen in the critically ill. Conditions of most relevance to the critically ill patient population are acute respiratory distress syndrome (ARDS), pneumonia and post-extubation stridor. Glucocorticoids also have a role in the management of acute respiratory failure due to asthma, chronic obstructive pulmonary disease, alveolar haemorrhage syndromes, acute lupus pneumonitis, and bronchiolitis obliterans organizing pneumonia (BOOP), radiation pneumonitis and pulmonary drug toxicity.