Marine biotoxins are produced by marine algae. During algal blooms at sea, these toxins end up in different sorts of seafood by filtration of contaminated water (eg mussels and oysters) or by eating contaminated food (eg crabs or lobsters). Two groups of marine biotoxins were included in this research: the so-called ‘DSP toxin s’ (‘Diarrhetic Shellfish Poisoning toxins’), lipophilic toxins that cause diarrhea and ‘ASP toxin s’ (‘Amnesic shellfish poisoning toxin s’), domoic acid and isomers, which can lead to nausea and neurologic symptoms. Both toxin groups are a threat to the Belgian population. For many years, food monitoring programs for marine biotoxins in seafood are implemented, based on reference methods described in European regulations and legislation. The shellfish included in these regulations, are species feeding directly on the toxin producing algae. In this study we want to go a step further and investigate whether the toxins can also be accumulated in crabs that feed on shellfish, and thus indirectly on the toxic algae. In addition, we examine the effect o f different processing methods on the toxin content o f the diverse types of common seafood.