Lymph node (LN) status is the most important prognostic indicator for the clinical outcome of patients in human solid cancer. Recent developments in sentinel lymph node (SLN) concept and technology have resulted in the application of this revolutionary approach to determine if cancer has metastasized. The underlying thesis in solid cancer biology is that metastasis generally starts in an orderly progression, often spreading through the lymphatic channels to the SLN. Thus, the logical approach is to harvest that specific SLN for thorough analysis. The most exciting possibility of selective sentinel lymphadenectomy (SSL) is that it will lead to early diagnosis of micrometastasis in regional LNs. Early diagnosis makes it useful as a clinical staging procedure, and opens up new opportunities to study micrometastasis and its evolution within the SLNs. New molecular and genetic tools may be used to dissect the mechanisms of lymphatic and hemotogenous routes of metastasis. If such mechanisms can be understood, new therapeutic advances may be developed to prevent the process of micrometastasis. *********************************************************************************** Minimally invasive surgery associated with reduced morbidity has transformed the management of cancer patients. Sentinel lymphadenectomy for staging and treatment of solid tumors is now standard of care in many settings. In this text, distinguished investigators review the technical aspects and clinical considerations related to this procedure. Steven T. Rosen, M.D. Series Editor.