The American College of Surgeons Oncology Group (ACOSOG) Z0030 study is a randomized, multiinstitutional, prospective trial designed to determine whether long-term survival is affected by mediastinal lymph node dissection (MLND) vs lymph node sampling (MLNS) at the time of pulmonary resection for lung cancer. We enrolled 1,023 eligible and /or evaluable patients with stage T1 or T2, N0 or nonhilar N1 lung cancer to either MLNS (n 5 498) or complete mediastinal lymphadenectomy (n 5 525). After analysis, we concluded that a complete mediastinal lymphadenectomy adds little morbidity to a pulmonary resection for lung cancer and found that the overall operative mortality for pulmonary resection was 1.4% (14/1,023). 1 The impact of MLND on long-term survival will be determined once long-term follow-up data of the study are mature.Because lymph node status is a main determinate of stage, and thus prognosis, complete lymph node dissection has been recommended for all patients undergoing surgical resection of lung cancer. However, what constitutes a complete lymph node dissection is not defi ned, and different terminology is used to describe various techniques of surgical lymph node assessment.