A SERIES of twenty-five cases of acoustic nerve tumours operated upon by a translabyrinthine-transtentorial technique, employing micro-surgical techniques is analysed from the point of view of preservation of the facial nerve after total removal. The size of the tumour, as expected, has been the most important factor in determining preservation of the structure. If there is to be a high rate of facial nerve preservation after acoustic nerve tumour surgery, the diagnosis must be made by the otologist (rather than the neurologist) who has the opportunity of diagnosing the lesion when it is still small.