Vestibular diagnosis of Menière's disease must be based on the results of an elaborate test battery. The latter should include a complete caloric test (stimulation with cold and warm water), carried out under nystagmographic control. Statistical analysis of caloric responses recorded in 100 normal test subjects by D.C. nystagmography show clearly that culmination frequency and culmination eye velocity are the most reliable parameters indicating an unilateral loss of function. With respect to the differential diagnosis - endorgan or neuronal lesion - only the galvanic test allows an unequivocal localisation of the site of the lesion. An analysis of 50 cases of Menière's disease reveals normal liminal and supraliminal galvanic responses without exception, thus indicating that the concomitant reduced caloric response is due to a lesion strictly confined to the vestibular endorgan. Hence the galvanic test may serve the same diagnostic purposes as supraliminal tests in pure tone audiometry.