Squamous cell carcinoma of the upper respiratory and digestive tract has a high risk for neck metastasis, which reduces the probability of regional control and survival. We analyzed the literature and our own experience to review the possible risk factors for the occurrence of metastasis. The most significant risk factors were: tumor site and size, grade of histologic differentiation, tumor thickness (tongue and floor of mouth carcinoma), vascular embolization, and perineural infiltration. A series of biomarkers has been studied over the last 10 years, but no one has proved to be significant enough for clinical use. Based on several multivariate analysis, it is recommended elective treatment of the neck for high-risk patients.