Trigeminal trophic syndrome is an unusual condition also known as trigeminal neurotrophic ulceration or trigeminal neuropathy with nasal ulceration. The diagnosis is suggested when ulceration of the face, especially of the ala nasi, occurs in a dermatome of the trigeminal nerve that has been rendered anesthetic by a surgical or other process involving the trigeminal nerve or its central sensory connections. A history of paresthesias and self-induced trauma to the area further support the diagnosis. Neurological deficits causing trigeminal trophic syndrome may result from surgical trigeminal ablation, vascular disorders and infarction of the brainstem, acoustic neuroma, postencephalitic parkinsonism, and syringobulbia. The following etiologies of nasal ulceration should be excluded: postsurgical herpetic reactivation and ulceration, syphilis, leishmaniasis, leprous trigeminal neuritis, yaws, blastomycosis, paracoccidioidomycosis, lethal midline granuloma, pyoderma gangrenosum, Wegener's granulomatosis, and basal cell carcinoma. In the case reported here, the diagnosis of TTS was made primarily as a result of previous experience with the syndrome, underscoring the importance of physician recognition of this unusual disorder.