The National Death Index (NDI) is a central computerized index of death record information on file in the State vital statistics offices. Working with these State offices, NCHS established the NDI as a resource to aid epidemiologists and other health and medical investigators with their mortality ascertainment activities. It is available to investigators solely for statistical purposes in medical and health research. This website provides access to information about NDI, incl. marching criteria, retrieval report, user's guide, application form and user fees.