The National Board of Health and Welfare and the National Central Bureau of Statistics in Sweden have jointly established a register containing, in addition to the data of the Swedish Cancer Register, information on occupation, economic activity, place of domicile, etc, from the 1960 population census. In the autumn of 1978 this Register was made available for interested scientists in all countries. It can be used for epidemiologic studies on the relationship that occupation, place of domicile, and similar factors may bear to the incidence of different types of cancer. The project was designated the Cancer-Environment Register. The present paper contains a synopsis of this register.