To confirm the diagnosis of sarcoidosis a characteristic X-ray and a positive histologic pattern is essential. In most cases one can get the histology by a rather simple bronchoscopy. In cases of negative bronchoscopic findings one should perform a mediastinoscopy, which can be done by an expert thoracic surgeon almost on outpatient basis. In rare cases the final diagnostic step is the open lung biopsy, preferably done on the right thoracic side, as the lung transplanting surgeons recommend for a possible lung transplant the left side.