The molecular evaluation of resection margins in patients with squamous cell carcinoma of oral cavity who underwent surgery. Field of cancerization concept. METHODS: We included 16 patients with oral cavity squamous cell carcinoma in any of their locations, without pre treatment, surgically treated in our hospital in the 2011 year. The surgical specimen was processed by the pathology department of our institution, through the traditional method, additional sectioned including the tumor and at least 0.5 cm margin non tumorigenic. Study was performed hematoxylin eosin and was supplemented with immunostaining for p53, PCNA, Ki-67, epidermal growth factor receptor and vascular endothelial growth factor receptor. RESULTS: The most important features of the 16 patients studied were: The majorities were male, the average age was around 60 years old; most of them were tobacco and alcohol consumers. The tongue was the most frequent location and most of the tumors were in an advanced stage (stage III y IV). In molecular evaluation all the markers were positive in the resection margins in 93.75 % of all patients. The cell proliferation markers such as PCNA and Ki-67 and the p-53 were positive 1.5 cm to 2 cm tumor with intense staining. Conversely, epidermal receptor grow factors and vascular endothelial grow factor receptor were positive up to 1.5 cm but with less intensity. CONCLUSIONS: In oral cancer can often observe molecular changes in the apparently healthy tissue surrounding the tumor to at least 15 mm.