Due to the scale of international fish and seafood trade there is a large potential for (un)intentional misidentification and/or deliberate fraud through species substitution. Several studies from all over the world indicate that this is common practice, especially for processed products (e.g. fish fillets, bivalves without shell) which lack characteristic morphological features. These studies also seem to indicate that the scale, as well as the products most prone to mislabelling differ among countries. The present survey aims at identifying fish and seafood products that are commonly mislabelled in Belgium and at optimizing available identification techniques. In this framework we sampled a broad range of fish, shellfish and other seafood at various supermarkets and involving various processing methods (e.g. fresh, frozen, smoked, pickled, cooked, and fried). Samples were identified by DNA barcoding and the resulting DNA-based identifications were compared with the commercial labels. In non-fish seafood samples several cases of mislabelling were detected. All fish specimens for which DNA barcodes were generated, however, appeared to be labelled correctly. At this stage of the analyses it is hard to identify a pattern towards specific taxa or treatments prone to mislabelling, yet it seems that bivalves, cephalopods and crustaceans are more often mislabelled when they are part of mixed packages (type: fruits de mer ), than when sold individually. In addition, crustaceans also appear to be mislabelled more often if caught in the wild than when farmed.