Anterior-posterior body sway was evoked with monopolar bi-aural galvanic stimulus of the vestibular nerves in normal subjects and recorded with a force platform, two experiments being conducted. In an experiment of paired design, 9 normal subjects showed an increase in anterior-posterior sway as compared with lateral sway when exposed to the stimulus. In a second experiment another group of 10 normal subjects were exposed to a galvanic stimulus between a neck electrode and two electrodes placed on the arms, but there was no change in the relationship between anterior-posterior and lateral body sway. It is concluded that monopolar galvanic stimulus of the vestibular nerves can induce anterior-posterior body sway, a phenomenon which can be utilised to investigate the vestibulo-spinal contribution in postural control in the anterior-posterior plane.