Nine of 10 adults, previously healthy patients who suffered cardiac arrest during or after anesthesia, recovered nearly complete neurological function when given iv phenytoin, 7 mg/kg. Phenytoin was given only after spontaneous heart beat and systolic blood pressure > 100 mm Hg had been restored and the diagnosis of neurological deficit had been established on the basis of unconsciousness, dilated and areflexic pupils as well as rigid and/or decerebrated posture. One patient recovered only partially, and eventually succumbed to other complications.