The European Food Safety Authority (EFSA) panel on contaminants in the food chain (CONTAM Panel) has carried out a series of risk assessments on marine biotoxins in shellfish. They followed the European Commission (EC) request asking EFSA to assess current EU (European Union) limits regarding human health and methods of analysis for various marine biotoxins as established in EU legislation. Six scientific opinions have been adopted and published on different classes of marine biotoxins namely okadaic acid (OA)-group toxins, azaspiracid (AZA)-group toxins, yessotoxin (YTX)-group toxins, saxitoxin (STX)-group toxins, pectenotoxin (PTX)-group toxins and domoic acid (DA). Currently scientific opinions on emerging marine biotoxins in shellfish are under discussion in the CONTAM Panel working group. They are due to be completed by July 2010. To carry out the risk assessments EFSA requested occurrence data from the EU member states (MS). In response some MS and Norway submitted on OA-, AZA-, YTX-, STX-, PTX-group toxins and DA for the period from 1999 to 2008. The occurrence data submitted for the different groups of marine biotoxins varied. The number of submitting countries was often limited and the number of results submitted varied considerably between the reporting countries. Also the analytical methods used for the analysis of marine biotoxins in shellfish varied. Most of the samples were analysed by high performance liquid chromatography (HPLC) coupled with a mass spectrometer (MS) or by other HPLC-methods such as HPLC-fluorescence detection (FLD) and HPLC-ultraviolet detection (UV). Also mouse bioassays (MBAs) were used, as they are the official reference methods prescribed in the EU legislation for the analysis of marine biotoxins in shellfish. Some of the submitted datasets contained high proportions of samples having concentrations below the limit of quantification (LOQ). For four groups of marine biotoxins a number of samples was analysed both by MBA and LC-MS/MS and these results were compared in the EFSA scientific opinions. A short overview on occurrence data reported to EFSA is presented here. More detailed information can be found in the respective EFSA scientific opinions on marine biotoxins (EFSA, 2007; EFSA, 2008a,b; EFSA, 2009a,b,c.d,e).