This thesis explores the avenues for the ecosystem approach to management in the Baltic Sea Region. This region is one of the most contaminated water bodies in the world, although the first Regional Seas Convention was created here and theregion has a long history of cooperation and environmental protection. The current environmental governance arrangements are examined with specific focuson governance structures, cross-sectoral integration and ecological boundaries.The ecosystem approach to management as both a tool and vision of holistic management of natural resources is traced through the evolution of environmental governance, as well as its manifestation in contemporary environmental policies in the region. It is found that the major EU directives, as well as HELCOM polices, promote the ecosystem approach and that its presence has increased inrecent years; it is now the major guiding principle in European marine governance. However, the governance structures impede implementation indifferent ways. The environmental problem areas in the region all require different governance arrangements, thus obstructing a holistic approach. The environmental problems per se also affect each other, necessitating far-reaching sectoral integration and cross-border cooperation, which at present is the major obstacle regarding implementation. The contemporary trends combining solid regionalisation through HELCOM with increased Europeanisation and macro regionalisation by different EU initiatives offer some promise, but the cross sectoral impediments must be resolved if the ecosystem approach is to become apractical approach and not just a policy principle.