The aim of our study was to estimate the concentrations of polychlorinated biphenyls (PCBs) in blue mussels (Mytilus edulis) originating from the Danish Straits and southeastern parts of the Baltic Sea, collected between 2003 and 2004. The samples taken from the ferry harbour of Gedser contained the highest amount of PCBs among all places analyzed (289±61.6 ng g^-1 wet weight), while in case of the Polish coast the highest concentration of these compounds was detected in samples coming from Gdynia Orłowo (117±25.3 ng g^-1). PCBs were not detected in the samples taken from Copenhagen (municipal beach), while the lowest concentration of these compounds on the Polish side was discovered in samples coming from Kuźnica (8±5.06 ng g^-1). It was also proven that blue mussels from the area of the Danish Straits, except for the ferry harbour of Gedser, are less contaminated with PCBs than those coming from the southeastern Baltic. In the samples taken from Gdańsk Bay (59± 53.0 ng g^-1) PCBs were detected, while in the samples coming from the open sea the PCB level was 23±10.7 ng g^-1. The obtained results indicate that the vicinity of ports and cities influences concentrations of PCBs in blue mussels. The results confirm usability of blue mussel in the research concerning levels of PCB pollution of the Baltic Sea environment.