In 1875 registration of causes of death in Denmark was established by the National Board of Health, and annual statistics of death have since been published. Until 1970 the national statistics were based upon punched cards with data collected from the death certificates. Since then the register has been fully computerized and includes individual based data of all deaths occurring among all residents in Denmark dying in Denmark. Furthermore, a microfilm of all death certificates from 1943 and onward is kept in the National Board of Health. The Danish Institute for Clinical Epidemiology (DICE) has established a computerized register of individual records of deaths in Denmark from 1943 and onwards. No other country covers computerized individual based data of death registration for such a long period, now 54 years. This paper describes the history of the registers, the data sources and access to data, and the research based upon the registers, presenting some examples of research activities.