The early diagnosis of acoustic neuroma is a desirable aim because it greatly decreases the surgical morbidity, particularly with respect to the brain stem and the facial nerve. Conventional audiometry remains the most important first line of investigation for the otologist. The author places the greatest reliance on the results of three tests: if the BERA, calorics and IAM tomograms are all normal, the chances of an acoustic neuroma are remote in the extreme. Ultimately the preoperative diagnosis must be made on the strength of positive radiology of the posterior cranial fossa, whether CAT scanning or by more traditional methods.