Metastasis is an extraordinarily complex process that remains to be a major problem in the management of cancer. Metastasis, which is a process in which primary tumors disseminate to secondary organs, is a major cause of cancer mortality. Metastatic tumors to the head and neck region are generally rare and they account for less than 1% of the metastatic tumors occurring in the body. Metastasis to soft tissue of the oral cavity is much rarer than jaw bones, because of rarity, metastatic tumors in the oral region are challenging for diagnosis. Although the oral cavity is not a common site for metastatic colonization, it is an interesting site because of the various and different tissues that may be involved in the metastatic process. This textbook illustrates the biological basis of the metastatic process in general, discusses the possible mechanisms by which metastatic tumours spread to the oral region, and summarizes the information in the literature concerning oral metastatic tumours.