Neurodegenerative disorders are among the most challenging and devastating illnesses in medicine. A heterogeneous group of chronic and progressive diseases, they include Alzheimer's, Parkinson's, and Huntington's diseases. Dentists faced with patients affected by one of these disorders are confronted with the major problems of cognition, mobility, and behaviour, as well as of dental maintenance. While treatment of patients with progressive neurodegeneration remains daunting, increased knowledge of the aetiology and pathogenesis of these diseases has provided new opportunities and a new understanding of their treatment needs. In this article, we briefly describe the effects of ageing on the brain, and introduce two of the major neurodegenerative disorders, Alzheimer's and Parkinson's diseases. The dental problems associated with these conditions include a decrease in oral hygiene, difficulty in controlling and retaining dentures, and purposeless chewing. Medications can result in xerostomia and consequent root caries and recurrent decay. Where possible, individuals with neurodegenerative disorders should always be treated by the same dentist.