To test whether <i>APOE</i> variation is associated with all-cause dementia in British South Asians, we analysed data from 51 104 volunteers in the Genes & Health study-a cohort study of British Bangladeshi and British Pakistani individuals who have undergone genotyping and consented for lifelong (England & Wales National Health Service) linkage to healthcare records. This evidence concerns the gene APOE and dementia.