To characterize the bioaccumulation and historical trends of polybrominated diphenyl ethers (PBDEs) in Deep Bay, an important water body between Hong Kong and main land China with a Ramsar mangrove wetland (Maipo), marine organisms and core sediments were collected to determine their PBDEs concentrations. Sediment core dating was accomplished using the (210)Pb method. PBDEs concentrations in fish ranged from 0.17 to 4.16 ng g(-1) wet wt., with a mean value of 2.00 ng g(-1) wet wt. Temporal trends of the target PBDE congeners levels in core sediment generally increased from 1948 to 2003, with the highest levels in top sediment, suggesting an ongoing PBDEs input. The average sedimentation flux of PBDEs was 0.25 ng cm(-2) a(-1), and the double time of total PBDEs concentration was ca. 12.3 a. Correlations between the biota-sediment accumulation factors (BSAF) of PBDEs and their corresponding octanol-water partition coefficient (K(ow)) were discussed.