During the period 1968-79, a total of 90 thoracotomies for lung metastases was performed in 76 adult patients (42 men and 34 women, aged from 16 to 72 years) treated at the Gustave Roussy Institute, Paris. Forty-three had carcinoma, 29 had sarcoma and 4 had melanoma. Thoracotomy was performed once in 64 patients, twice in 10 patients and 3 times in 2 patients. Complete resection could be performed in 88%. The operative mortality rate was 1.1%. Four benign lesions were encountered. The survival rate was 56% at 2 years and 43% at 3 years. Several prognostic factors were identified. The indications for pulmonary metastasectomy within the overall strategy of metastatic cancer treatment are discussed.