The National Health Data Dictionary, Version 11 contains a summary of changes to Version 10 of the data dictionary.Continued use of the Dictionary will help ensure that data elements are collected uniformly from all services and jurisdictions throughout Australia and thereby improve the quality of information for community discussion and public policy debate on health issues in Australia. The format for data definitions continues to be based on the international standard for defining data elements issued by the International Organisation for Standardization and the International Electrotechnical Commission. The full version 11, including both the changed and the unchanged items, is available on the AIHW Knowledgebase - Australia's Health, Community Services and Housing Metadata Registry on the AIHW web site.