The aim of the present study was to clinically, morphologically, and immunohistochemically correlate the expression of cytokeratins (CKs) 7, 10, 13, 14, 16, and 19 in 30 cases of tongue squamous cell carcinoma (SCC) with disease outcome, metastases, clinical stage (tumor, node, metastasis [TNM]), and histological grade of malignancy proposed by Bryne. Statistical analysis (chi2 test) showed that only histological grading was not significantly correlated with the clinical variables. CK expression varied in the samples analyzed. CK 10 expression was significantly correlated with the presence of metastases, and the expression of CK 16 was related to disease outcome and also to TNM stages III and IV. These results indicate that metastases and TNM are effective prognostic indicators. The histological grading proposed by Bryne did not reflect the biological behavior of the tongue SCC cases studied. Analysis of some intermediate CK filaments can reflect the biological behavior and aggressiveness of some tongue SCCs.