An overview is presented of the Non-Indigenous Species (NIS) of algae and invertebrates recorded in the marine and brackish coastal waters of Normandy in France. Out of the 152 NIS found, 86 have been introduced through shipping (ballast waters and fouling) and 66 through aquaculture activities. A total of 95 NIS are linked to a Pacific origin and 32 come from the northwestern region of the Atlantic. Among the 152 NIS identified, only nine show an invasive demography in Normandy waters. The first introductions occurred in the middle of the 19 th century and became frequent by the beginning of the 20 th century. However, over 50% of the NIS so far recorded were found only during the three last decades.