Selective symmetrical necroses of many tegmental brain stem nuclei including motor cranial nerve nuclei, superior and inferior colliculi, cuneate and gracilis nuclei, and others are known as hypotensive brain stem necrosis (Gilles 1969). We found such lesions in eight infants and seven adults. Examination of their clinical records revealed a well documented episode of cardiac arrest in each case. Cardiac output was restored in all but one patient 5 min to 4 h after the beginning of resuscitation. All patients remained comatose in a decerebrate state up to their death 17 h to 4 weeks after admission. Our findings and a review of the literature indicate that this type of lesion relates specifically to cardiac arrest. The term "hypotensive brain stem necrosis"is a misnomer and should be replaced by the term "cardiac arrest encephalopathy".