This is the first study on parasite fauna of Mytilus galloprovincialis Lamarck, 1819 in Turkish waters. Mussel samples were collected monthly at 3 sampling stations on the coast of Sinop on the Black Sea in the period between August 2012 and July 2013. A total of 1740 mussels were examined for parasites using standard parasitological investigation procedures. The parasites identified included the following: 2 protozoans, Nematopsis legeri (32.12%) and Peniculistoma mytili (6.72%); 1 turbellarian, Urastoma cyprinae (6.32%); 1 trematode, Parvatrema duboisi (4.54%); and 1 polychaeta, Polydora ciliata (2.24%). All identified species are illustrated in figures and constitute new records of Turkish parasite fauna.