Many marine species are threatened, and given the importance of biodiversity indices in the current European marine policy, taking stock of existing species and species diversity is crucial. Zooplankton form the basis of the pelagic food web, acting as staple food for fish larvae and adult pelagic fish, but are very susceptible to a changing climate. Inventorying zooplanktonic diversity is therefore important. Based on monthly sampling campaigns in 2009 and 2010, an update is provided on the zooplankton species list for the Belgian part of the North Sea. A total of 137 taxa are listed, some of which had rarely or never been observed in the area. This inventory revealed several species new to the Belgian marine species list: the calanoid copepod Metridia lucens , the cyclopoids Oithona similis and Giardella callianassae , the hydrozoans Amphinema dinema and Eutima gracilis , the mysid Acanthomysis longicornis , the polychaete worm Tomopteris helgolandica , the cladoceran Penilia avirostris and the monstrilloid copepod Cymbasoma germanicum . Additionally, we identified several males of C. germanicum , which have never been described before. Brief discussions are presented on spatial distribution and abundance of all taxa.