This study deals with the presence of Mytilus galloprovincialis on the Mediterranean green crab, Carcinus aestuarii Nardo, 1847 as an epibiont. Crab samples were collected by means of single-entry fyke nets at 6 different locations selected in the Cardak Lagoon. A total of 22 specimens of M. galloprovincialis (1-9 ind. per crab) on different body parts of 4 crabs were recorded. This is the first report about the occurrence of M. galloprovincialis on C. aestuarii.