Marine spatial planning is an important tool to achieve a more ecosystem-based governance approach to marine ecosystems. Marine ecosystems often transcend national jurisdictional boundaries, so the compatibility of national policies and legal structures are important prerequisites for transboundary marine spatial planning. This paper explores marine spatial planning in the North Sea ecosystem and analyzes whether national policies and legal structures in the Netherlands and Norway are compatible enough. Both countries have an extensive body of law regulating the different uses of the North Sea and have also developed integrated management approaches for 'their' respective parts of the North Sea. The paper demonstrates that marine spatial planning in regional sea areas is complicated when national legal frameworks and governance structures and traditions are very different. ; publishedVersion