The present document compiles the scientific information collected by the experts for the Joint FAO/IOC/WHO ad hoc Expert Consultation on biotoxins in bivalve molluscs held in Oslo, Norway, 26-30 September 2004 to answer the request of scientific advice expressed by the Codex Committee for Fish and Fishery Products (CCFFP). In order to satisfy the many requests received by FAO to disseminate the information collected over these years since 2004, the data and information available were edited and updated in 2009. The document is organised in three main parts that present scientific and technical information necessary for risk assessment, monitoring and surveillance programmes and, in addition, illustrate how the CCFFP used international expertise to advance and finalize international standards for bivalve molluscs.