Résumé : The trigeminal trophic syndrome is a rare complication following central or peripheral injury of the trigeminal nerve typically characterized by unilateral distribution of anaesthesia, paraesthesia and ulceration. In one third of cases it is preceded by an iatrogenic damage of the trigeminal nerve, in another third by a history of stroke. Other causes include head trauma, intracranial tumours, herpes virus infection, degenerative diseases of the CNS and idiopathic. Little is known about the pathogenesis. Contribution of neurotrophic factors and an altered sympathetic activity is assumed but a pivotal role of self-mutilation is generally accepted. We report a case of a patient who developed a strictly unilateral crescent ulcer of the ala nasi in addition to an extensive ulceration of the forehead and scalp following herpes zoster ophthalmicus.