Squamous cell carcinoma (SCC) is the most prevalent malignant neoplasm of the oral cavity. Cervical lymph node metastasis is a prognostic factor of paramount importance in patients with oral squamous cell carcinoma. We retrospectively analyzed the clinicopathologic features and the association of these features including degree of differentiation, tumor size, T stage, lymphovascular invasion, perineural invasion, and depth of invasion—on the risk of neck node metastasis in 25 adult patients who had been treated with surgery for primary squamous cell carcinoma of the oral cavity. Depth of invasion and other pathologic features were determined by reviewing the pathology specimens. The association between the prevalence of neck node metastasis and the depth of invasion was observed to be statistically significant, but there was no significant association between neck node metastasis and tumor T stage or degree of differentiation. We conclude that the prevalence of neck lymph node metastasis in patients with squamous cell carcinoma of the oral cavity increases as the tumor depth increases, as has been shown in previous studies. It is interesting that tumor size, which is the most important component in the TNM system for staging oral squamous cell carcinoma was not significantly associated with neck node involvement.