Intoxications with mussels containing algal toxins continuously take place in coastal regions. They are mostly caused by algal blooms. Intoxications are reported more frequently because the consumption of mussels is rather high in some nations. Therefore, it is important to identify these toxins. HPLC has been shown to be a sensitive method for the detection of PSP and DSP. In this study, mussels collected from the Bosphorus region and sold at the whole sale fish market in Istanbul were analyzed. The samples were taken in the season (May to September) during which the sea water temperatures are highest. Throughout the study period the toxin levels were beneath the detection limits.