Thoracic lymphadenopathy consists of mediastinal and/or hilar lymphadenopathy. Thoracic lymph nodes are anatomically one of the most complex groups of the lymphatic network in the body and describing them could be nerve wracking if there is no proper understanding of the locations, its systemic divisions and its significance in diseased states. Thoracic lymphadenopathy is one of the most common radiological findings seen on the CT scan of thorax. The incidence of these findings have particularly increased in the era of lung cancer screening with low dose CT scan of the chest. The differential diagnosis for mediastinal and hilar lymphadenopathy is broad and spans from being reactive to benign disease to lung cancer or metastatic cancer. In this book, we have tried to simplify the lymph node stations based on the latest IASLC guidelines, done a very comprehensive review about mediastinal and hilar lymphadenopathy in different disease states and provided the pathway to diagnosis. This book also gives a detailed account of noninvasive testing including CT chest and PET CTs. This book also discusses in detail the advanced endoscopic and non-endoscopic procedures like EBUS-TBNA, EUS and Mediastinoscopy that we have at our disposal for the diagnosis of thoracic lymphadenopathy. The indications, contraindications, sensitivity and specificity of each procedure is discussed in detail.