The important physiological and pharmacological considerations in pinniped anesthesia are outlined, based on experiences with the harp seal (Pagophilus groenlandicus). Preanesthetic drugs were avoided and induction was achieved with inhalation of halothane and nitrous oxide, or with thiopental sodium administration into the extradural vein. Maintenance anesthesia was achieved with halothane using controlled ventilation. Some of the anesthetic problems encountered are discussed.