The authors have made a full anatomical description and roentgenological study of the internal auditory or labyrinthine artery. The internal auditory artery seldom arises from the basilar trunk and reaches the inner ear without giving off collateral branches to the cerebellum; more often it originates as a branch of the cerebello-labyrinthine artery near to the internal auditory meatus. The first segment of the internal auditory artery goes through the pontocerebellar cistern (precanalicular or cisternal segment) ending with a slight angle close to the internal auditory meatus; at this level the intracanalicular segment arises and follows the inferior wall of the internal auditory canal with a fluctuating path. Angiographic studies made on a group of patients affected by lesions of different nature affecting the petrous portion of temporal bone have shown that the roentgenological visualization of the internal auditory artery offers greater accuracy in diagnosing expanding processes in the region of the ponto-cerebellar angle and opens new horizons for the study of those diseases of the ear, in the pathogenesis of which a vascular factor plays an important role.