The effects of cyclopropane, nitrous oxide, thiopental, ether, halothane, and methoxyflurane on sodium transport in the isolated toad bladder were studied. All agents affected sodium transport in the same way: stimulation at low concentrations; inhibition at high concentrations. Stimulation may be the result of positive interaction with catecholamines on the serosa, inhibition the result of a mucosal effect. The balance between stimulation and inhibition of sodium transport in vitro appeared unrelated to the anesthetic effect in vivo.