The distribution of selected polycyclic aromatic hydrocarbons (PAHs) in mussels (Mytilus galloprovincialis) in the coast of the Turkish Straits System (TSS) was determined using high-performance liquid chromatography (HPLC). According to the results, the most important contributors to PAH concentrations in mussels were chrysene, fluoranthene and benzo(a)pyrene (BaP). Due to its carcinogenic character, BaP is known as one of the most significant congeners of PAHs and the highest concentration of BaP has been found to be 8 mu g g(-1) in Kadikoy station. The most polluted mussels were collected from the regions affected by shipping activities such as Kadikoy, Kumkapi and Tekirdag. In this study, origins of pollution were determined using the ratios of individual PAH compounds. The main pollution origin is found as both pyrolytic and petrogenic at most stations.