The presence of the demersal Asian copepod Pseudodiaptomus marinus is reported for the first time in the southern bight of the North Sea, in both Calais harbour and the coastal waters off Gravelines, France. This is the first record of P. marinus in the Atlantic Ocean sector and the North Sea area. The species was collected in January and October 2010, and in January, February and April 2011. The very low number of collected individuals (0.2 to 4.0 ind.m-3) and the capture of only two ovigerous females and of a few numbers of copepodid CV stages suggest that the species survives and actually reproduces in both sites but does not manage to develop an abundant population. The presence of P. marinus in Calais harbour and coastal waters of the southern North Sea supports recent observations of other Asian species in the same area and suggests a passive transport via ship’s ballast waters.