Background: After the liver, the lungs represent the most frequent site of metastasis from primary tumours. Surgical treatment of lung secondary neoplasms leads to a significant improvement in survival., Methods: Between 1960-1997, 178 patients with lung metastases underwent surgery at the Thoracic Surgery Department of Turin University in a total of 193 operations. A retrospective study was made in order to identify the prognostic factors which influenced final survival in this population., Results: Overall survival was 47% after 2 years and 20% after five years. Prognosis was not influenced by the size of metastases, the type of surgery, adjuvant therapy and the number of operations on the same patient. On the other hand, useful prognostic factors were found to be the histological type of the primary tumour, the original site of the neoplasm, the number of metastases and, above all, the disease-free interval (DFI)., Conclusions: Lung metastasectomy is an important therapeutic aid in selected patients, whereas the preoperative evaluation of the above prognostic factors enables a reasonably precise prognosis to be made in most patients.