Detection of mediastinal, hilar, and intrapulmonary lymphadenopathy is crucial for staging lung cancer. Precise staging is essential for determining treatment options and assessing patient response to therapy. Definitions of the lymph node locations used in staging have been based on surgical landmarks relevant to mediastinoscopy and thoracotomy [1] (Fig. 1). These surgical landmarks are not always easily translated to cross-sectional imaging. Cross-sectional diagrams at six levels accompanied the original American Thoracic Society nodal staging system [2], but to our knowledge, correlation with CT scans has not previously been done. Because mediastinoscopy is not always performed for staging [3], CT may be the only procedure used for evaluation of intrathoracic lymph nodes. This pictorial essay provides cross-sectional definitions of regional intrathoracic lymph node stations, depicts them on CT, and describes recent changes in the lymph node staging system for lung cancer.