The association between frontal dementia and motor neurone disease has been known for years now although its existence as a nosologic entity in its own right is still subject to debate. Lack of strict histological criteria and inspecificity in complementary tests which might otherwise lend weight to such a diagnosis prevent our considering it as much more than a mere clinical syndrome. We present here the case of a 56 year old female patient who developed a type of dementia with frontal characteristics associated with motor neurone disease. We discuss the clinical picture and review the relevant literature.