On 17 August 1999 a powerful earthquake struck the eastern part of Marmara Region and Izmit Bay, the most industrialized and populated area of the region. Environmental effects of the earthquake and subsequent refinery fire were partly investigated by several scientists (Okay et al., 2001, 2003; Tolun et al., 2001, 2006; Balkis, 2003; Unlu and Alpar, 2004; Karakas and Pekey, 2005). As a part of the previous efforts, in this study, the levels of total PCBs, sum of the marker PCBs and TEqs in mussels collected immediately after and 1 year later the earthquake were presented. Total PCB (# 1-209) levels in mussels from different coastal locations were found between 5.47 and 14 ng/g in September 1999 and between 11.2 and 36.0 ng/g in June 2000. June 2000 samples from throughout the Bay contained higher quantities of total, marker PCBs and TEq values when compared with the before earthquake values. The elevated concentrations of PCBs in mussels collected after the earthquake implies an input of PCBs to the water column form different sources such as underlying sediments and/or land-based sources such as industrial inputs. Although WHO-TEq values found in this study for Izmit Bay (0.4 +/- 0.1 - 1.4 +/- 0.7 pg/g) are lower than the proposed values for fisheries products (4 pg/g) by EC Regulation 199/2006, considering the TDI value as 2 pg WHO-TEq/kg bw (COT, 2001) it was concluded that consumable mussels from Izmit Bay pose a risk for health.