The reliability of the sentinel lymph node (SN) technique has been established for more than ten years in T1-T2 oral cavity and oropharynx squamous cell carcinoma. Although most authors stress the necessity of rigorous implementation, there are no agreed guidelines. Moreover, other indications have been described, in other anatomical areas of the upper aerodigestive tract and in case of previous surgery or radiotherapy. SN expert teams, under the GETTEC head and neck tumor study group, conducted a review of the key points for implementation in head and neck cancers through guidelines and a review of classical and extended indications. Reliability depends on respecting key points of preoperative landmarking by lymphoscintigraphy, and intraoperative SN sampling and histological analysis. The SN technique is the best means of diagnosing occult lymph node involvement, whatever the primary tumor location, T stage or patient history.