This article tackles the problem of regionalisation of Slovenia from the integrated perspective of water management. When propositions to divide Slovenia into several regions (provinces) (with proposals to make between 3 and 14 regions) were made, very different and numerous parameters have been taken into account. The article examines the regionalisation problem from the integrated water management perspective that was introduced into the Slovenian water legislation by the European Water Directive, adopted in 2000. The article also summarises the main directions of integrated water management, contained in Water Act that was adopted in 2002 and is still in force. On the basis of integrated water management foundations in European legislation, the article uses the division of Slovenia into water districts as a professional basis for a comparison between different proposals for division of Slovenia into regions. Although it is true that a hydrographical division of Slovenia into water districts cannot be the most important basis for regionalisation, one may notice that a division of Slovenia into three regions (Western Slovenia (Koper), Central Slovenia (Ljubljana), Eastern Slovenia (Maribor)) and partially division into six regions would be Ally in line with bases for integrated and (by definition) territorial water management.