Head and neck squamous cell carcinoma(HNSCC) is among the most common malignances worldwide. Patients with HNSCC often develop primary tumors at multiple sites and have tendency for local recurrences following curative resectional surgery. Field cancerization theory presumes that, after repeated carcinogenic exposures, the entire superficialepitheliium of the upper aerodigestive tract has an increased risk for developing (pre)malignant lesions because of multiple genetic abnormalities. This theorywell explains the strong potential with malignant transformation and loco-regional recurrence in HNSCC, and helps to better understand the pathogenesis, and thus provides a new idea for prevention and treatment of this disease. This paper will give an overview of field cancerization, including the concept and its clinical application.