Read before the Society, 27 May 1955 Statistics of causes of death are probably the most important single item in any vital statistics system for the planning and administration of health services necessarily depend on them and on statistics of morbidity. Nearly all civilised countries have developed statistics of causes of death during the past century, but although morbidity statistics are closely associated with mortality statistics, few countries at present publish comprehensive statistics of illnesses. Much still remains to be done to improve the quality of statistics of causes of death in many countries, and to ensure that they are internationally comparable. For the improvement of these statistics and for the formulation of proposals in regard to the preparation and analysis of morbidity statistics, a study of multiple causes of death is essential.