Objective: To determine the rate of spontaneous tumour shrinkage in a group of patients with sporadic vestibular schwannoma managed with a 'wait and scan' approach. Patients: All patients with a unilateral cerebello-pontine angle tumour resembling a vestibular schwannoma were registered prospectively in a national database in Denmark. Patients registered with tumour shrinkage were identified and all computed tomography and magnetic resonance imaging scans retrieved, re-evaluated and related to the clinical data. Results: Of 1261 observed patients, 48 displayed spontaneous shrinkage (3.81 per cent). Mean absolute shrinkage was 6.25 mm, equivalent to 52.1 per cent. Absolute shrinkage correlated with tumour size and follow-up period, whereas relative shrinkage was significantly greater for tumours which were purely intrameatal at diagnosis. There was no correlation between age and the degree of shrinkage. Conclusion: Four per cent of sporadic vestibular schwannomas shrink spontaneously. These findings substantiate the 'wait and scan' strategy for tumours with a largest extrameatal diameter of up to 20 mm.