Interim Biogeographic Regionalisation for Australia (IBRA) version 6.1 represents a landscape based approach to classifying the land surface of Australia. 85 biogeographic regions and 405 sub regions have been delineated, each reflecting a unifying set of major environmental influences which shape the occurrence of flora and fauna and their interaction with the physical environment across Australia.The IBRA Version 6.1 data consists of two datasets. IBRA bioregions, which is a larger scale regional classification of homogenous ecosystems, and sub regions, which are more localised.IBRA Version 6.1 is the result of refinement of the IBRA Version 5.1 and version 6.0 boundaries due to better data availability amongst some states and territories and also based on alterations by the states/territories along the state borders. The refined boundaries were jointly defined by the Commonwealth, State and Territory nature and conservation agencies. Those jurisdictions to refine their data in this version of IBRA include New South Wales, Queensland, Victoria and Western Australia. There are 53 newly named sub regions and 5 have been renamed from version 5.1. Whilst there has been a refinement of sub-regional and associated bioregional boundaries in Qld, Vic and western NSW, the new sub-regions are found principally in eastern NSW. In WA changes relate to moving the western boundary of Yalgoo bioregion to the coast, truncating the northern portion of the Geraldton Sandplains bioregion.Nominal attributes that make up IBRA are: climate, lithology/geology, landform, vegetation, flora and fauna, and landuse. The use of these attributes varies across the jurisdictions and for further information individual jurisdictions should be contacted.