This issue of Thoracic Surgery Clinics is dedicated to the lymphatic system in thoracic oncology. Scientific knowledge and technical options in this field of thoracic pathology have shown a significant improvement in recent years thanks to the joint efforts of surgeons, oncologists, radiologists, interventional pulmonologists, and pathologists. Advances in technology and active clinical research in the last decades have contributed to increase the diagnostic accuracy and to modify the therapeutic approach when considering the lymphatic involvement in thoracic tumors. In particular, the introduction and progressive affirmation of some innovative diagnostic tools such as positron emission tomography and ultrasound-guided endoscopic procedures (EBUS, EUS) havepartially modified the modern diagnostic approach to chest tumors. These techniques havemade it possible to reduce the invasiveness of mediastinal staging and to extend the possibility of preoperative cytological or histologic sampling to lymph node stations that are not reachable by conventional surgical