Different methods were used to study the physiology and anatomy of the vestibular system. 1) A primary vestibular cortical area in the cat was located and tested for somatosensory inflow by recordings of vestibular evoked potentials and extracellular single unit activity. 2) The enzyme horseradish peroxidase was used as a retrograde anatomical tracer to identify thalamo-cortical vestibular pathways. 3) Vestibular disturbances aused by the industrial solvents methylchloroform and styrene were recorded by electro-oculography. Positional nystagmus was seen above a concentration of 75 ppm of methylchloroform and 40 ppm of styrene in blood. 4) A clinical vestibular rotatory test procedure is described and evaluated in an animal model before and after unilateral labyrinthectomy. A long time reduction in gain is seen at higher rotational frequencies and a trend that serves to define the side of a peripheral lesion is superimposed on the oscillatory eye movements after unilateral vestibular damage.