Sentinel lymph node (SLN) mapping has become a common procedure in the treatment of breast cancer and malignant melanoma. Its primary benefit is that it enables surgeons to avoid nontherapeutic lymph node dissection and the complications that follow. There are also several studies of the use of SLN mapping in the treatment of non-small cell lung cancer (NSCLC) reported in the English literature, and all present evidence for the existence of SLNs in NSCLC. Nevertheless, SLN mapping is not widely used in the treatment of NSCLC for several reasons: first, special precautions are required to minimize exposure when radioisotopes are used as tracers; second, it is difficult to detect the blue dyes used as tracers within anthoracotic thoracic lymph nodes; and third, major complications comparable to the arm edema seen in breast cancer or the lymphedema and nerve injury seen in melanoma are not seen with mediastinal lymph node dissection (MLND). To address these issues, new techniques are being developed by groups at several institutes, including our own. We believe that SLN mapping will enable surgeons to more precisely stage NSCLC, after which more sensitive techniques can be employed on a limited amount of tissue to detect occult micrometastatic disease with less cost and effort. SLN mapping can also be applied to video-assisted thoracic surgery (VATS) for NSCLC, enabling surgeons to avoid nontherapeutic and technically difficult MLND often necessary with traditional open surgery. For all of these reasons, we think that SLN mapping will be useful in the treatment of NSCLC, and that further development aimed at making SLN mapping a practical surgical procedure is warranted.