IT HAS BEEN PROVED that the number of acoustic tumors found is in direct relationship to the index of suspicion for such a lesion by the otologist. The possibility of an acoustic tumor should be entertained in all cases of unilateral cochlear or vestibular loss of unknown origin. We feel that these patients should undergo an accurate neurological and audiometric evaluation as well as a clearly defined plan of radiographic examinations. In final analysis, the presence or not of an acoustic tumor must be proved radiographically. A conventional radiographic examination of the skull is always performed in order to rule out the presence of a gross lesion not necessarily related to the problem under investigation. At the same time the petrous pyramids are carefully examined by tomography, which is a simple and safe procedure and constitutes, in our opinion, the most valuable screening test. Tomography should always be performed in