Neck node metastasis of oral cancer can be diagnosed by bimanual palpation, CT, MRI and neck sonography and the final diagnosis can be confirmed by pathologic evaluation of the neck nodes after elective neck dissection. When we meet clinically negative neck node(N0 neck) of oral squamous cell carcinoma, the treatment modality of the neck nodes with the primary lesions are so controversial. The usually used methods are various from close observation to elective radiation and elective neck dissection. The methods can be chosen by the primary size of the carcinoma, site of the lesions and the expected percentage of the occult metastasis to the neck. We reviewed the 86 patients from 1996 to 2006 who were diagnosed as oral squamous cell carcinoma, whose necks were diagnosed negative in radiographically and clinically. According to TNM stage, the patients were in the states of N0 and treated by surgery using mass excision and elective neck dissection. We compared the differences between the clinical diagnoses and pathologic reports and would discuss the needs for elective neck dissection.