Four Arctic walrus each weighing approximately 450 kg were anesthetized for various surgical procedures. Premedication consisted of meperidine hydrochloride (Demerol) at 2 mg/kg and midazolam hydrochloride (Versed) at 0.03 - 0.05 mg/kg. This was followed 20 - 30 minutes later by intravenous Thiamylal sodium (2.5%) given to affect. The walrus were incubated by hand and placed on a large animal ventilator with isoflurane and oxygen. Maintenance levels of isoflurane ranged from 1.0 - 2.0%. Cardiac activity was monitored by ECG and body temperature by rectal thermometer. Recovery in the first animal was longer than expected so Naloxone hydrochloride (Nancan) was given either intravenously or intramuscularly in the subsequent 3 individuals. Recovery time improved after Nancan administration.