We assessd the feasibility and problems associated with sentinel lymph node (SLN) study in 13 cases of oral and pharyngeal squamous cell carcinoma (SCC) that were neck-node-negative clinically. The primary sites were the tongue (n = 10), other sites in the oral cavity (n = 2), and the mesopharynx (n = 1). The day before surgery, tracer was injected into the submucosa around the tumor, and scintigraphic images were acquired 2 hours later. The SLN was identified intraoperatively with a handheld gamma probe, and neck dissection, including the SLNs, was performed. Radioactivity within the nodes was confirmed with a well type scintillation counter, and all resected lymph nodes were histologically examined for metastasis. The SLN was identified in every case. There were regional lymphnode metastases in 4 cases, and metastasis to the SLNs was present in all of 4 cases. Thus, the SLN concept was valid for head and neck SCC, sentinel node navigation surgery (SNNS) was thought to be applied in stage NO SCC of the head and neck. If SNNS is performed, about 70% of patients do not require neck dissection. SNNS is feasible and cost-effective in these cases. We used two different tracers: phytate and tin colloid, and found that phytate was more useful. To avoid the effects of the shine-through phenomenon, it was thought that some directions of lymphoscintigram should be taken. For intraoperative identification of the SLNs, care should be taken to the angle of gamma probe. SLN study leads to clarify each patient's lymphoid flow mapping, and it is also useful to determine the dissection area of selective neck dissection.