ABSTRACTThe quality of the North Sea has become a topic high on the political agenda. Various claims have been made about quality deterioration but hard evidence has been less available. The paper reviews these concerns, summarizes the scientific evidence and considers the specific contaminants involved, together with estimates of inputs and the available controls. The new initiatives stemming from the Ministerial conferences and the evolving legislation should go a long way towards producing reassurance on the one hand and solutions to real problems on the other.