Lymphangiograms performed via direct cannulation of lymphatic ducts demonstrate drainage of the lymph into a specific lymph node center, the so-called SLN. Contrast materials such as lipiodol, injected directly into the tissue (e.g., tongue) can demonstrate the SLN. As the neoplastic cells can be carried through the lymphatic ducts, the SLN is the first filter in the lymphatic pathway, and the SLN is indeed the most likely regional node to harbor metastatic carcinoma. The results of these efforts challenged the surgical community worldwide to recognize the importance of the concept of SLN. This concept needs to be inexpensive and easily applied in daily practice. Recently, brilliant investigators have found that using "blue dye" and or radioactive tracers are a resourceful way in identifying SLN and have applied the benefits in their daily practice. Morton [15] using the "blue dye" and Krag [1] using radioactive tracers are pioneers in the application of these concepts in other malignant diseases. The SLN concept today is feasible to apply in the investigation, diagnosis, staging and treatment of almost all solid tumors in human pathology. Numerous elegant reports have proved the validation of the concept [2, 7-9, 11, 12, 16, 17, 20, 21, 26-28].