An 82-year-old woman was admitted to the ICU with septic shock and multiple organ failure. Despite the lack of a persistent septic focus she continued to be dependent on large doses of norepinephrine whilst receiving adequate antimicrobial therapy. After a trial treatment with hydrocortisone the norepinephrine infusion could be withdrawn within a few days and she made a full recovery. In the case of seriously ill patients the diagnosis 'relative adrenocortical insufficiency' is predominantly made on the basis of the clinical picture. The remarkable clinical response to the administration of hydrocortisone (400 mg in the first 24 h) confirmed the diagnosis. The dosage of vasopressors can be reduced remarkably quickly. The stimulatory test for adrenocorticotropin hormone (ACTH) has no added value as reference values for critically ill patients are not available and because the results do not predict the response to the treatment.