Cornelia de Lange is a genetic syndrome which affects between 1/10.000 and 1/60.000 neonates, but its genetic bases are still not clear. Its principal clinical characteristics are the delay in growth and development, hirsute, structural anomalies in the limbs and distinctive facial characteristic. Dental problems are frequent and include: ogival palate, micrognathia, dental malalignment, delayed teething, microdontic teeth, periodontal disease and dental erosion produced by gastric reflux. Discussed is the case of a 29 year old patient affected by the syndrome in question, which presents the principal clinical characteristics. The patient?s general state of health is acceptable, without cardiac or respiratory alterations. The intraoral exploration shows policaries, periodontal disease, persistence of the temporal teeth and ectopic molars. After completing the necessary pre-operatory preparations, the entire odontological treatment was carried out under general aesthesia, due to the patient?s total lack of collaboration.