The growth of vestibular schwannoma (VS) was investigated in a series of 123 patients with 127 tumours during 3 periods: 1973 to 1993 (mean observation period 3.4 years), 1973 to 1996 (mean observation period 3.8 years) and 1973 to 1999 (mean observation period 4.2 years). Three sets of growth results were obtained. At the end of the first period, 94 tumours (74%) exhibited measurable growth, 23 tumours (18%) no measurable growth and 10 tumours (8%) negative growth. Tumour growth was observed in 104 tumours (82%), no tumour growth in 15 tumours (12%) and negative growth in 8 tumours (6%) at the end of the extended observation period. Growth was observed in 108 tumours (85%), no growth in 11 tumours (9%) and negative growth in 8 tumours (6%) subsequent to the third observation period. However, the results can be interpreted in another way: 52 patients (42%) are alive, tumour growth required no intervention; 23 patients (19%) died due to non-tumour-related causes; and 35 patients (28%) were previously treated and alive by the end of the third observation period. Together with other factors, the results reported here should be considered when timing of surgery is to be decided.