In the differential diagnoses of facial pain, it is useful to consider the psychogenic types and then the sites of dysfunction or disease. This review emphasizes those facial pains in which examination of the patient is normal or nonspecific, and the cause is not obvious. Atypical facial pain is a diagnosis of exclusion without known pathophysiologic mechanisms, and is often psychogenic. Dysfunction of the muscles of mastication (myofascial pain dysfunction) is a common cause of facial pain; the acronym TMJ (temporomandibular joint) is best reserved for demonstrable disease of the joint. Other organic diseases and pathophysiologic processes affecting the muscles and bone, mouth, eyes, ears, nose, throat, blood vessels, and cranial nerves, and pain syndromes affecting the central nervous system are discussed. If the underlying cause of pain cannot be found and eliminated, other therapeutic approaches are discussed.