The study of 25 cases of 'benign paroxysmal position vertigo' showed us that irrigation of the ear opposed to the injured side inhibited this nystagmus. In these patients, it is difficult, not to say impossible, to provoke rotatory nystagmus, either by the caloric test (Brünings position II) or by the rotatory test in frontal plane. The significance of these observation is discussed and ascribed to a central compensation system.