Primary mediastinal malignancies should be treated aggressively using a multidisciplinary approach since some are curable. Surgery is indicated in almost all cases of mediastinal masses with the exception of malignant lymphomas. The question of operability must be placed at the beginning of diagnostic measures in a mediastinal mass. Exact decisions about local operability are often only possible after thoracotomy. Long lasting diagnostic maneuvers are therefore to be avoided. Histological assessment of masses in the middle or anterior mediastinum is possible by mediastinoscopy or other methods. Thus in malignant lymphomas or metastases thoracotomy can be avoided. In the other mediastinal spaces exact histology remains unknown until thoracotomy. If exploration shows inoperability, mass reduction is performed to decrease the space-taking process and to provide better chances for radiotherapy and chemotherapy. Primary radiotherapy and/or chemotherapy are indicated in malignant lymphomas and germ cell tumors. After these measures the indication for surgical excision in tumors has to be proved. X-ray screening techniques need to be improved to aid in early detection, higher extirpation rates, and thus better chances for cure. Because the amount of cases in individual departments is low multicenter collaboration will be required to define the optimal combined modality approach.