During the past 25 years the authors have diagnosed over 1,600 acoustic neuromas. In almost all of the cases surgery for the removal of the tumor was performed shortly after the diagnostic test. However in 35 cases one or more follow-up imaging studies was performed since the patients refused surgery, or surgery was not performed because of the poor general condition of the patients or the small size of the lesion, particularly in individuals of advanced age. In the latter group there was a clear understanding that surgery would be performed if the follow-up study showed progression of the lesion.In this paper the authors review the evolution of the tumor in the 35 cases, try to establish the rate of growth in cases where the tumor became larger, and correlate tumor evolution to patient's age and clinical findings.