The occurrence and wide distribution of eutrophication effects due to excess nutrient loading in certain parts of the North Sea are an issue of concern. Elevated nitrogen and phosphorus concentrations are clearly detectable in many estuaries and along most of the coastline from northern France to Denmark, sections of the south-eastern English coast, and in parts of the Skagerrak and the Kattegat. It is generally acknowledged that the high nutrient load can cause increased biomass and extensive phytoplankton blooms. These may occasionally include harmful species. Negative impacts include periodic disturbances such as oxygen depletion and subsequent increased mortality of benthic organisms, as well as long-term changes in the abundance and diversity of animal and plant communities. The Contracting Parties of the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) have agreed to take all possible steps to prevent and eliminate pollution and to take the necessary measures to protect the maritime area against adverse effects of human activities. OSPAR’s objective with regard to eutrophication is to combat eutrophication in the OSPAR maritime area, in order to achieve a healthy marine environment where eutrophication does not occur by 2010. Following this, the Commission has undertaken to identify by 2002 the eutrophication status of all parts of the Convention Area which will reported to the OSPAR Ministerial Meeting in 2003. This report comprises an assessment of the eutrophication status of the Swedish parts of the Kattegat and Skagerrak as a contribution to this joint evaluation.