Shellfish poisoning is caused by a group of toxins developed by planktonic algae (dinoflagellates), upon which the shellfish feed in most cases. The main groups of biotoxins harmful for human beings are: DSP, NSP, ASP and PSP. In the case of DSP, the effects include diarrhea, nausea, vomiting and abdominal pain, and it is found in humans very soon after the ingestion of contaminated bivalve mollusks. They also induce tumors of the stomach. Total quantities (measured in the whole mollusks or any edible part separately) should not exceed the following limit for okadaic acid, dinophysistoxins and pectenotoxins together, 160 micrograms of okadaic acid equivalents per kilogram and for yessotoxins, 1 milligram of yessotoxin equivalent per kilogram. Modern chemical techniques such as immunoassay, phosphatase test or chromatography (HPLC, LC-MS) are very suitable for the detection of DSP.