From 1960 to 1986, 69 patients with low grade neuroendocrine tumours (LGNT) of the lung were admitted to our institution. Of these, 36 were male and 33 were female. The mean age was 43 years with a range of 9-76 years. Sixty-eight patients were operated upon of whom 11 had metastatic mediastinal lymphnodes. A complete follow-up ranging from 3 to 25 years was obtained in 61 patients. Actuarial survival was 95% at 5 years and 87% at 10 years. The most important factor influencing the prognosis was mediastinal lymph node involvement. In 9 patients with mediastinal lymph node metastases at operation, the survival at 5 and 10 years was 75% and 46%, respectively, with highly significant difference (P less than 0.0001) as compared with the nonmetastatic group. In conclusion, bronchial LGNT are generally benign, but encompass a potential for malignancy. The prognosis depends on the presence of regional lymph node metastases. The choice of adequate surgical treatment depends on the size, location and aggressiveness of the tumour and the status of the mediastinal lymph nodes. The condition of the lung parenchyma distal to the lesion must be taken into account.