Carcinomas of the oral cavity and oropharynx constitute approximately 2% to 5% of head and neck cancers. Alcohol abuse and tobacco chewing, including chewing Shamma, predispose individuals to the development of cancer in the oral cavity. CT and MR imaging are best suited in the evaluation of cancer of the oral cavity and oropharynx. CT in the axial and coronal planes with 3- to 5-mm sections is the primary modality and is best in the evaluation of bony erosion of the mandible and maxilla. Furthermore, lymph node metastases in the neck are optimally evaluated by contrast CT with 5-mm axial sections. MR imaging is preferred for soft tissue assessment because of the greater contrast resolution. It is therefore the first modality in the assessment of tongue carcinomas, oropharyngeal cancer, and tonsillar lesions. The MR examination should be performed with thin-section imaging, applying T1, T2, and T1-GD-DTPA in the axial and coronal planes, with sagittal sections added for paramidline lesions involving the tongue, lips, anterior floor of the mouth, subdivided according to anatomic locations. The local spread, lymph node metastases, prognosis, and therapeutic approaches vary with the location of the lesion represented by a carcinoma either squamous or undifferentiated in 90% of cases. Some malignant lesions may mimic a benign tumor, such as the adenoid cystic or mucoepidermoid carcinoma. Histopathologic diagnosis is therefore necessary for the final diagnosis before treatment by surgery or radiotherapy. PET scanning is indicated in the following instances: in search of an unknown primary tumor in patients who have a neck mass secondary to carcinoma, if a recurrent carcinoma may be present, when there are metastatic N0 lymph nodes in the neck, or where CT is inconclusive for metastatic lymph nodes in the neck.