A retrospective study of 53 patients with squamous cell carcinomas of the oral cavity and oropharynx was undertaken to evaluate histopathologic parameters in predicting cervical lymph node metastasis. Biopsy and surgical specimens were examined for degree of differentiation, pattern and depth of stromal invasion, lymphatic-vascular invasion, and lymphoplasmacytic response in relation to metastasis. The incidence of lymph node metastasis in tumors showing grade III type diffuse invasion (71.4%) and with stromal invasion of more than 8 mm in depth (83.3%) was significantly higher than that of tumors with well-demarcated boundaries (44.4% to 5.2%) and superficial invasion (35.3% to 8.3%). Lymph node metastasis also increased in the presence of lymphatic-vascular invasion by tumor cells, whereas the degree of differentiation and lymphoplasmacytic response was not related to metastasis. Thus, the pattern and the depth of stromal invasion and the presence of lymphatic-vascular invasion were important indicators in prediction of cervical lymph node metastasis. Prophylactic neck dissection is advocated when grade III type diffuse invasion, invasion exceeding 8 mm in depth, or grade II type invasion accompanied by a 4 mm to 8 mm depth of invasion is observed in a biopsy specimen.