The analysis of mortality by cause, as well as of morbidity, calls for an instrument that groups the diseases according to common characteristics, that is to say, a classification of diseases. The WHO Internatinal Classification of Diseases, in its Ninth Revision, is currently in use. This classification first appeared in 1893; its Tenth Revision is being proposed for 1993. This present paper describes the origins of this international classification, making special references to John Graunt, William Farr and Jacques Bertillon as well as describing the evolution that has occurred through its successive revisions. Initially it was a classification that included only causes of death. After the Sixth Revision included all the diseases and causes of medical consultations, thus allowing its use in morbidity. For the tenth and later revisions, a "family" of classifications is proposed, for a great variety of uses in health services, administration and epidemiology. Some critical observations on the current international classification of diseases are also presented.
Diseases classification; Mortality; Morbidity