THE USE of electronystagmography (ENG) offers promise as a finer and more quantitative method of study of the vestibular apparatus than gross studies. We, in the United States, have lagged behind our European confreres in its use. However, ENG presents two major problems. There are difficulties with maintenance and repair. These were formerly insurmountable. Even a major university center with electronic engineers had difficulty when foreign apparatus was purchased, since acquisition of parts sometimes meant a delay of months. Also, the electronics and physics of the procedure are often difficult for the clinical otologist. Jung, a neurologist has stated that ENG measures the brain stem (and the peripheral labyrinth), while electroencephalography measures the brain cortex. The objectives of this study are to provide some understanding of the mechanics and operation of ENG, and to provide details on the use of ENG as a clinical procedure. It would be ideal for