The glycerol test helps to establish the differential diagnosis between Ménière's disease and other vertigo disturbances, but the test becomes very long and in its primary form informs us only about the cochlear response to the osmotic changes produced by glycerol in the inner ear, and tells us nothing about the vestibular response. In patients with unilateral endolymphatic hydrops we have performed simultaneously the glycerol test with audiometric and craniocorpographic (CCG) control. The response of the vestibular apparatus to the glycerol becomes evident in 84.5% of cases on average in 30 min. By contrast, the variation in the hearing-threshold appears in only 54% of cases and required on average 60 min. At the same time, CCG is easier and shorter to perform than audiometry, showing five different types of response to glycerol. The combined use of audiometry and CCG allows us to predict with sufficient accuracy the response of the endolymphatic hydrops to the treatment, simplifying the therapeutic indication and the choice of the surgical technique.