The microbiological monitoring and classification in Europe is based on faecal indicator E. coli monitoring in live bivalve mollusc. As a result of the implementation of the microbiological threshold defined by European legislation since 01/01/2006, almost all A quality areas have disappeared, and most areas show B quality. Percentage-wise, the C quality category is more frequently observed for areas with burrowing bivalves like clams and cockles. From these results, a few elements can be pointed out : - firstly : the contamination levels are different between the burrowing and non burrowing bivalves. Thus, it is important to examine separately the evolution for each type of species. The evolution since 1989 shows for the oyster and mussels an improvement of the quality from 1989 to 2002. Since then, a decrease is observed (less A quality areas and some more C quality areas), confirmed by statistical analysis for some points. For cockles and clams, an increasing number of zones have sufficient data to assess their quality (thanks to continuous improvements in the monitoring network). - Secondly : the contamination situation and its evolution are very different from one area to another and should be examined closely for each area, - Thirdly : the alert monitoring has increased since 2004, and has become now an important part of the monitoring. Preventative alerts alone account for 32 %.