When considering the previously described pathways of invasion, we can more simply individualize anatomical structures at risk of tumor invasion. The most important example is the Tumor Node tract is located in the sublingual space and contains nerves, blood vessels, and lingual lymph nodes, which demonstrated an important role in relapse and poor prognosis when involved. Oncological compartments enclose all these structures at risk that need to be handled and removed along with the tumor in order to achieve adequate radicality. This redefinition of radical surgery differs from the classical conception of the wide margin technique, where radicality is obtained by maintaining a wide clear margin around the tumor without identifying or considering the specific muscle or anatomical structures removed. The aim of this chapter is to define the concept of oncological compartment in its application in oral cancer surgery.