Trigeminal neuralgia (TN), also known as tic douloureux, is a pain syndrome often recognizable by the patient’s history alone. Trigeminal neuralgia is characterized by facial pain often accompanied by a brief facial spasm or tic. Pain distribution is unilateral and follows the sensory distribution of cranial nerve V, typically radiating to the maxillary (V2) or mandibular (V3) area. At times, both distributions are affected. Physical examination will usually eliminate alternative diagnoses. Signs of cranial nerve dysfunction or other neurologic abnormality exclude the diagnosis of classic trigeminal neuralgia and suggest that pain may be secondary to a structural lesion. Nomenclature is nonintuitive. Classic trigeminal neuralgia includes all cases without established etiology after investigation, as well as those with potential microvascular compression of the fifth cranial nerve. In symptomatic trigeminal neuralgia, the pain syndrome is secondary to tumor, multiple sclerosis, or other structural abnormalities.