The National health data dictionary (the NHDD) is a national resource which health jurisdictions use to ensure the consistency and comparability of all data collected under the National Health Information Agreement. It is increasingly being used as a resource to standardise data collections that are not mandatory for national collection. It is vital that the health care community continues to standardise the meaning and representation of data used for both clinical purposes and statistical analysis. The use of the NHDD is an important step in this process. With the comparability of data collected based on definitions in the NHDD, information collected by jurisdictions throughout Australia can provide meaningful input to community discussion and public policy debate on health issues in Australia. The aim of such discussion is to improve the quality and safety of health care for all Australians. Version 14 has been downloaded from METeOR which is an internet registry for development, registration and dissemination of metadata based on the latest version of the international standard ISO/IEC 11179 Information technology-Metadata registries (MDR) in 2003. The Dictionary is available online at .