Aim: Around four million people are affected by a rare disease and 15 per cent can become manifest in the orofacial region, e.g. craniofacial dysplasia such as cleft lip and palate, dysgnathia, and hypodontia. Orthodontics forms a major field in rare diseases. Dentists and orthodontists are often the first to come in contact with young patients who are affected by a rare disease. There are no guidelines in dentistry on how to treat patients with rare diseases or which orofacial manifestation can help to find a diagnosis. The aim is to establish a 'database for orofacial manifestations in people with rare diseases - ROMSE' in order to improve diagnosis and treatment. To allow a standardised documentation of orthodontic cases, it is necessary to unify the classifications of dysgnathia. Materials and method: Since 2011 material from various databases such as Orphanet, OMIM, and PubMed, was evaluated. Starting in 2013 the gathered information was incorporated into a web-based, freely accessible database at http://romse.org. The dysmorphological classification should be the guideline for orthodontists to classify the dysgnathia and to standardise the documentation of people with rare diseases. The classification form is freely available at the ROMSE website. Results: So far 529 rare diseases with orofacial manifestations have been listed in the ROMSE database. About one-third of those diseases or syndromes show dysgnathia. Especially the sub-classification of dysgnathia seems to be difficult since most of the patients were not analysed according to a standardised classification. Wrong or double assignments are the result. Conclusions: Rare diseases and their symptoms come with difficult challenges regarding their therapy. By setting up a ROMSE, a platform is provided for dentists and orthodontists to work on interdisciplinary treatment strategies. A consistent and beyond dentistry classification of dysgnathia can avoid wrong assignments. Schlagwörter: rare diseases, dysgnathia, orthodontics