249 thoracotomies for lung-metastases were performed in 202 patients at the 2nd Dept. of Surgery of the Vienna University Clinic till 1989. Age ranged from 2 to 78 years, 14 patients were younger than 18 years. The primary tumour was a carcinoma in 143 cases, a sarcoma in 45 cases and a melanoma in 14 patients. The primary tumour in the young patients was osteosarcoma in 8 cases, Ewing sarcoma in 2 cases and Wilms tumour in 2 patients. With a minimal follow up period of 2.5 years the 5-years-survival after metastasectomy was 42% for patients with carcinoma and 29% for the sarcoma patients. None of the patients with melanoma survived 5 years. A significant difference was found between the carcinoma and sarcoma groups with respect to survival rate. A prognostic factor was the disease-free interval in carcinoma patients. Actuarial post-thoracotomy survival in patients with osteogenic sarcoma was 34% at 5 years and 18% in the soft-tissue sarcoma group. Size of lesion, vitality of the metastases and the disease free interval correlated with survival in the osteogenic group, whilst the number of lesions was of importance in the soft-tissue group. On account of the lesser functional morbidity and the enablement to assess both lungs for treatment, the median sternotomy is recommended for cases with bilateral lung metastases. The results justify an aggressive surgical approach for the treatment of lung metastases.