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 greater than 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.