Oral squamous cell carcinoma (OSCC), is the most common malignancy of oral cavity, and the sixth most frequently diagnosed cancer worldwide. This tumor type is associated with poor prognosis, and most OSCC patients are diagnosed after the cancer has reached an advanced stage. The over expression of NF-κB p65 has been associated with OSCC progression and lymph node metastasis. Hence, the present study analyzed the expression of NF-κB p65 in OSCC from Korean patients. Immunohistochemistry for NF-κB p65 was performed using 12 normal oral mucosas (NOM), 16 oral leukoplakia (with/without dysplasia), and 58 OSCC patients samples. Immunoreactivity was semi-quantitatively scored and the correlation between the expression of NF-κB p65 and clinicopathological parameters of OSCC patients was analyzed. Immunohistochemical staining revealed that NF-κB p65 expression level increased in oral leukoplakia with dysplasia and OSCC. Moreover, the immunoexpression of NF-κB p65 appeared to be associated with age, recurrence, TNM stage, and lymph node metastasis in OSCC patients (p<0.05). These results indicated that NF-κB p65 can play a role as oncogene in OSCC. Moreover, NF-κB p65 may play an important role in both oral carcinogenesis and OSCC patient outcome. It may be considered as another new malignant biomarker of OSCC.