Primary mediastinal tumours (PMT) are rare, they include many different histological types, but lymphomas, thymomas and neurological tumours make up most of these tumours. Their symptomatology is often poor and they are in many cases discovered by routine thoracic radiography. Diagnosis mainly relies on medical imagery and on biopsy by mediastinoscopy or by CT-Scan controlled needle puncture. The treatment depends on the histological type (radiotherapy, chemotherapy, surgery). Median sternotomy is preferred to tackle anterior and middle mediastinum PMT, since it offers a large operative field and is more comfortable for the patient than classic thoracotomy, which will be reserved to tackle posterior mediastinum PMT.