Trigeminal neuropathy is commonly seen as a disorder of sensation in the distribution of the fifth cranial nerve. An 18-year-old girl was referred to our hospital because of a severe anterior open-bite deformity with a long face after presurgical orthodontic treatment. Surgical plan was maxillary posterior impaction with anterior advancement, mandibular setback operation, and genioplasty with vertical chin reduction in one stage. One month after surgery she had still difficulty closing her mouth. With the help of her hands, she could close her mouth fully on normocclusion. Weakness of the jaw-closing muscles was confirmed with muscle testing. She had impaired sensation to light touch and pinprick in the distribution of the maxillary and mandibular divisions of the bilateral trigeminal nerves. T1-weighed MRI of the brain showed bilaterally atrophy of the muscles innervated by the trigeminal motor nerve (i.e., the masseter, medial and lateral pterygoids, and temporalis muscles). We thoroughly evaluated our patient through history and clinical, laboratory, electrophysiological, and radiological examinations. The motor and the sensory V2 and V3 branches of the trigeminal nerve were congenitally damaged. As far as we know, this case is the first bilateral congenital trigeminal sensorimotor neuropathy presented with maxillo-mandibular and a severe open-bite deformity.