The management of acoustic neuromas is directed towards early diagnosis and surgical removal. The routine use of magnetic resonance imaging (MRI) has permitted the diagnosis of very small acoustic neuromas. However, it is becoming evident that not all acoustic neuromas will grow if left alone. In our series we followed 44 patients with acoustic neuromas for an average of 30.5 months and assessed their growth by serial MRI scanning. We followed 20 intracanalicular and 24 cerebello-pontine angle lesions. In both groups the phenomenon of arrested growth was demonstrated in the majority. When growth did occur, it did so at a variable rate, but was always evident within the first year. We recommend an initial observation period of 1 year in all small neuromas. If growth occurs at this stage removal is indicated. When growth does not occur serial MRI review at increasing intervals is indicated.