In this study, the activity concentrations of Po-210 and Pb-210 were determined in mussel samples (Mytilus galloprovincialis) collected from the Turkish coast of the Aegean Sea. The samples were collected seasonally for a period of two years (2004-2006) at six coastal stations (Canakkale, Dikili, Foca, cesme, Didim, Bodrum). Mussels were separated into several groups according to their size (1-4,4-6, >6 cm). The results showed that Po-210 concentrations in mussels varied between 53 +/- 4 and 1960 +/- 60 Bq kg(-1) dw. The highest activity Po-210 concentrations were determined in winter samples of mussels with a shell length of 4-6 cm from Didim. In general, it was observed that the Pb-210 concentration levels in mussels were lower than Po-210 concentrations. The Po-210/Pb-210 activity concentration ratios exceeded unity for all mussel samples and averaged 26.0. The inter-site differences seen in Po-210 concentrations can be due to both the natural background levels of sites and industrial activities. (C) 2011 Elsevier Ltd. All rights reserved.