In October 2003, Croatia declared an 'Ecological and Fisheries Protection Zone' in the Adriatic Sea. However, in June 2004 Croatia decided to delay the implementation of that Zone to European Union member states. Then, in December 2006, it decided to fully implement the Zone from 1 January 2008 - while eventually, on 13 March 2008, to again postpone the implementation on EU countries. Developments and underlying reasons in the changing jurisdictional picture in the Adriatic Sea are the subject of this article. Key Adriatic Sea features, trends in uses of its living resources and maritime space, and resource conservation and marine pollution concerns are presented. Developments leading to recent national legislation and positions on maritime jurisdiction by Croatia, as well as Italy and Slovenia are discussed. These regulations, positions and developments are assessed from the law of the sea perspective; also relevant policy perspectives, including aspects of EU membership, are included.