The aim was to study oral health and oromotor function in individuals with rare diseases. A disease is defined as rare when it affects no more than 100 individuals per million population and leads to a marked degree of disability. An affected nervous or musculoskeletal system, cognitive impairment, neuropsychiatric disorders and craniofacial malformations are common in rare diseases and may all be risk factors for oral health and oromotor function. In 1996-2008, 1,703 individuals with 169 rare diseases, aged 3-67 years, answered a questionnaire about general health, oral health and orofacial function and 1,614 participated in a clinical examination. A control group of 135 healthy children, aged 3-14 years, was also included in the study. Oral health was examined by a dentist and oromotor function by a speech-language pathologist. The participants with rare diseases were recruited via family programmes, referrals to the clinic and research projects, while the controls were randomly selected from a Swedish municipality. In the diagnosis group, 40% had moderate or severe problems coping with dental treatment, 43% were receiving specialised dental care. Difficulties related to tooth brushing were common compared with the controls. Approximately two thirds of the study group and the control group were caries free. Frontal open bite, long face and high palate were common in individuals with rare diseases compared with controls. Oromotor impairment was a frequent finding (43%) and was absent among the controls. There was a significant correlation between oromotor impairment and certain structural deviations and oral-health issues. Compared with healthy controls, individuals with rare diseases often have difficulty coping with dental treatment and managing tooth brushing. Dysmorphology and oromotor dysfunction are frequent findings in this population and they often require extra prophylactic dental care and access to specialised dental care in order to prevent oral disease.