This article focuses on the use of the ecosystem approach to management (EAM) in the Baltic Sea Region (BSR). Based on selected criteria for EAM, the article traces and compares the impact of EAM on HELCOM's Baltic Sea Action Plan (BSAP), the EU Water Framework Directive (WFD), the EU Marine Strategy Framework Directive (MSFD) and the EU Maritime Spatial Planning Directive (MSPD). Starting from the assumption that institutional interplay determines the impact of the EAM on marine policies, the article examines how different forms of interplay (interplay through cognition, commitment and compliance) affect the spread of EAM and its implementation in the BSR. The study finds strong interplay between HELCOM's BSAP and the EU's MSFD. Although HELCOM is still an important player in marine governance in the BSR, since it includes Russia, taking over responsibilities for the implementation of EU legislation has repercussions and affects its independence. Copyright © 2017 John Wiley & Sons, Ltd and ERP Environment