The mentally handicapped exhibit a 3 times higher incidence of malocclusions and related functional problems than the general population. In contrast there is little available literature relating to the orthodontic treatment of handicapped patients. Based on published articles on orthodontic treatment of disabled patients the following recommendations can be given. First of all for each patient a ‘problem list’ should be drawn up, based on the diagnosis. In this list the orthodontic problems are formulated. Additionally, the list makes clear who is responsible for providing services related to orthodontic care, such as oral hygiene and transportation of the patient to the orthodontist. When deciding whether or not orthodontic treatment should be administered to a patient with a mental handicap the same functional and aesthetic considerations as with any other orthodontic case must be taken into account. Furthermore, the severity of the handicap and possible associated psychosocial and medical limitations as well as the extent to which it will be possible to treat the patient have to be considered. Contraindications are a severe mental handicap, inability to remain still in the dental chair, insufficient co-operation of parents/carers, open bite resulting from abnormal oral function, and a mild malocclusion. The orthodontic treatment should aim for an acceptable result, and not for orthodontic perfection.