Benign tumours in the posterior mediastinum are often asymptomatic until they reach a considerable size. Technically it is easier to remove the tumour when it is small, but these patients are often asymptomatic and therefore the tumours are rarely found before the patients become symptomatic. During 2010 three patients underwent resection of large benign tumours in the posterior mediastinum with a diameter more than 10 centimetres. We discuss, when should large benign tumours in posterior mediastinum be resected. We conclude that symptomatic patients with large benign tumours should be referred directly for surgery independent of size while asymptomatic patients should be followed regularly and referred for surgical treatment if their tumour increases in size because surgery may be hazardous as size of the tumour increases and more likely to be associated with major postoperative morbidity.