Cancers of the oral cavity are most frequent during the 6th to 8th decades and tobacco and alcohol are major risk factors. Diagnosis must be made by bimanual palpation and biopsy. Local invasion is best evaluated by CT-scanner and Magnetic Resonance Imaging for the primary tumor and by ultrasonography for neck nodes. For therapeutic and prognostic goals, staging of the tumor must be estimated before first treatment according to the AJCC and the UICC classification.