The presence of marine toxins in shellfish products could lead to fatal food poisoning. Monitoring programs to control levels of toxins establish monthly or even weekly sampling in production areas. Opening or closure of harvest areas would depend upon the results obtained. Post-harvest and end product testing is also carried out in some countries. Currently, paralytic (saxitoxins), ammesic (domoic acid) and lipophilic toxins (okadaic acid and derivatives, yessotoxins, pectenotoxins and azaspirazids) are legislated.