The factors relating to lymph node metastasis occurring in association with carcinoma of the tongue have been investigated clinically and histopathologically by many authors. Nevertheless, accuracy in predicting lymph node metastasis has not yet been attained. The present study describes the results of analysis performed in an attempt to predict lymph node metastasis of carcinoma of the tongue. Ninety-eight patients with squamous cell carcinoma of the tongue who were treated at our institution were investigated. Among the 98 patients, lymph node metastases were histologically proven after neck dissection in 40 patients. For statistical analysis in the present study, the quantification theory Type II of Hayashi (1954) was employed for discriminatory analysis. According to this discriminatory analysis, the correlations between the clinical (age, tumour size, N-category) and histopathological (degree of keratinization, mitoses, structure, mode of invasion) findings and metastasis were assessed on the basis of the partial correlation coefficients; these coefficients for each finding were not greatly different from each other and 74 out of 98 patients (76%) could be differentiated between patients with metastasis and without metastasis accurately. The prediction of lymph node metastasis by such discriminatory analysis had significant validity.