The sand content in edible part of blue mussels is important from a sensory point of view. Up to now there was almost no information available on the distribution of sand within the body of the mussel. The main share of sand in individual quick frozen mussels seems to be located in the hepatopancreas in comparison with other parts of the body like gills or mantle (mussel meat). At the end of the catching season an increase in sand content was observable in the whole mussel as well as in the hepatopancreas. The reason for this seems to be the immobilisation of sand in the hepatopancreas. This immobilisation makes the removal of sand by conditioning (watering) much more difficult in comparison to the removal of sand which is located in the gills or in the mantle. A size distribution of the grains of sand depending on the tissue investigated could not be observed. The size of sand grains seems mainly to be influenced by the catching ground.