A thorough knowledge of thoracic anatomy is of fundamental importance to the thoracic surgeon. Surface anatomy is an often-neglected component of traditional topographic anatomic teaching, but a proper understanding of the relationship of surface features to deeper structures is invaluable in the clinical assessment of a patient and in the interpretation of radiologic imaging. Familiarity with thoracic surgical landmarks is a prerequisite for the successful placing of a thoracic incision. Knowledge of the intrathoracic anatomy and level of the diaphragm based on surface landmarks is useful for interventional procedures, such as tube thoracostomy. Knowledge of the chest wall musculature is essential in the use of muscle flaps for reconstruction.