A major purpose for gathering descriptive statistics is to allow comparisons of data over time and among different places. In the case of public health it has been particularly important to make such comparisons utilising diagnostic information. Without a standard measuring tool which remains fixed for periods of time and which is applied uniformly from place to place, meaningful comparative analyses of diagnostic information would not be possible. The International Classification of Diseases is such a standard tool. This presentation briefly traces the history of the development and revision of various versions of this International Classification of Diseases and presents the background leading to the current activities associated with the Tenth Revision of this important health statistical and epidemiological disease classification.