In this pilot study, hazardous substances in the North Sea were assessed and classified using the HELCOM Chemical Substances Status Assessment Tool (CHASE). The study was based on monitoring by Belgium, Denmark, France, Germany, the Netherlands, Norway, Sweden and the United Kingdom. Together, 1350 locations (1155 for sediment and 195 for biota) were used resulting in 966 matrices sampled in the open-sea and 506 in coastal areas. CHASE is a multi-metric indicator-based tool developed for the HELCOM integrated thematic assessment of hazardous substances in the Baltic Sea. CHASE produces an integrated assessment and classification of “hazardous substances status”. This can be in particular advantageous for use in remedial action plan and, in particular, for the sciencebased evaluation of whether the North Sea is undisturbed by hazardous substances.