Oral cancer is a malignant tumor of the oral cavity mucous membrane which is caused by the mutation of epithelial cells. The most common causes include cigarette smoking and consumption of alcoholic beverages. It can develop from precancerous lesio ns, with leukoplakia and erythroplakia being the most significant ones. Other precancerous lesions of the oral cavity include the oral lichen planus, actinic cheilitis and submucosal fibrosis. Oral cancer usually occurs in the horseshoe­shaped area of the mouth which consists of the floor of the oral cavity, the lateral and ventral parts of the tongue, the lingual part of the lower alveolar ridge, the retromolar area and the palatal arches. The disease is initially asymptomatic, and it is clinically manifested either as white or a mixture of red and white lesions on the oral mucosa, or as ulcerations that do not heal in the span of two weeks. Ulcerations with indurated and raised edges or exophytic formations that fill the oral cavity develop in the later stages. Very often, the first sign of oral cancer can be an enlarged, fixed, and painless lymph node in the neck, which is an indication of metastasis. Oral cancer primarily forms metastases in a lymphogenous manner, and in more severe cases it can also metastasize hematogenously to distant organs. The disease is diagnosed by biopsy of the changed mucous membrane and by a pathohistological analysis of the biopsy taken. Treatment depends on the localization of the tumor, its stage, the lymphogenic/distant metastases, and the general health of the patient. In the initial stages of the disease, cancer is surgically removed, and in advanced stages, radiotherapy and/or chemoradiotherapy is used in addition to the surgical treatment. The doctor of dental medicine plays an important role in early detection of oral cavity cancer, as they can spot potentially malignant changes of the mucous membrane and refer the patient to a specialist. Early detection of the disease results in a better prognosis, simpler treatment and greater survival rate.