The hypocycloidal polytomographic temporal bone studies performed on 2683 patients were reviewed, and the radiographic appearance of the vestibular aqueduct was evaluated. Within this group of 5366 ears, forty-seven ears (1%) in twenty-six patients demonstrated a large vestibular aqueduct (diameter greater than 1.5 mm). A review of the relevant embryology, anatomy, and physiology is reported. A discussion of hypocycloidal polytomography and computed tomography of the temporal bone as well as a discussion of the Mondini dysplasia is also presented. The twenty-six patients underwent a battery of audiometric and vestibular function tests. These data were compiled and correlations made, allowing for a more complete characterization of the large vestibular aqueduct syndrome.