Background Familial factors are clearly associated with an increased risk of developing late onset Alzheimer's disease (LOAD). However, there is emerging evidence to suggest that familial factors may also influence clinical phenotype. To date, most studies have focussed on familial influences upon age of onset or duration of illness and few studies have compared the frequency of non-cognitive symptoms between familial and sporadic LOAD. Objective To describe the clinical phenotype, with an emphasis on non-cognitive symptoms, of patients with LOAD and to explore familial differences. Method 374 patients with LOAD were recruited from the community based Camberwell Dementia Case Register and a comparison made of the clinical phenotype of patients with and without a first degree family history of dementia. Results A first degree family history of dementia was found in 27% of fully ascertained cases. An earlier age of onset was found in familial cases (77.2 years compared to 78.3 years, p