OBJECTIVE: Overexpression of the epidermal growth factor receptor (EGFR) family is common in oral squamous cell carcinoma (OSCC). Therefore, we analyzed the expression profiles of the four EGFR family members (ErbB1, ErbB2, ErbB3, and ErbB4) in OSCC of Japanese patients. STUDY DESIGN: Sixty-eight primary tumors and 18 normal oral mucosal tissue specimens were evaluated in this study. We analyzed EGFR family members using quantitative polymerase chain reaction and immunohistochemistry, as well as their relationships with clinical factors. RESULTS: The expression level of ErbB1 messenger RNA (mRNA) was markedly increased in OSCC. By comparing the gene expression levels of EGFR family members in OSCC tissues that had lymph node metastasis with those in the absence of lymph node metastasis, we found that ErbB4 mRNA expression was increased significantly. There was also a significant correlation between the mRNA expression level of ErbB4 and those of ErbB2 and ErbB3 in cases with lymph node metastasis. Moreover, we confirmed protein expression of ErbB4 in the cytoplasm and membrane of tumor cells, which was stronger in cases with lymph node metastasis. CONCLUSIONS: ErbB4 is an independent marker for lymph node metastasis in OSCC.