Brain depression in a patient with severe multisystem disease can be a diagnostic challenge, particularly when the patient is maintained on artificial life-support systems.A case report is presented of a 13-year-old girl with severe pneumonia who was treated with prolonged cardiopulmonary bypass during which time she developed a clinical picture simulating brain death with marked depression of cerebral cortical activity on two successive EEGs. Following correction of some of her metabolic defects, the patient showed marked improvement of cortical function.Multisystem disease can be so severe as to produce a clinical picture of brain death. We wish to emphasize that brain hypofunction of depression is best evaluated by both clinical examination and the EEG, and that neither one alone is sufficent to conclude that cerebral death has occurred.