Polybrominated diphenylethers (PBDEs) are found ubiquitously in marine environments worldwide. Sediment is the major sink of PBDEs, with the congener BDE 47 being most abundant. In this study, laboratory experiments were carried out to test the hypothesis that contamination of BDE 47 at environmentally realistic sediment concentrations can alter polychaete larval settlement. Using multiple-choice experiment, settlement of three polychaete species (Pseudopolydora vexillosa, Polydora cornuta, and Capitella sp. I) on four types of spiked sediment was studied and compared: (i) low BDE 47 concentration (0.5 ng g-1 dry weight); (ii) high BDE 47 concentration (3.0 ng g -1 dry weight), (iii) hexane (solvent control), and (iv) natural sediment (control). Our results showed that settlement of P. vexillosa and Capitella sp. I larvae was significantly promoted, while settlement of P. cornuta reduced, at high BDE 47 concentration in sediment compared with the respective controls under both short- (24 h) and long-term (4 week) exposures. After 4 weeks, body burden of BDE 47 in all polychaete species was directly related to the spike concentration, and body length of settled juveniles of P. vexillosa and Capitella sp. I at the high-concentration treatment was significantly longer compared with that of other treatments and controls. For the first time, we demonstrated that environmentally realistic concentrations of BDE 47 in sediment can affect polychaete settlement in species-specific and dose-dependent manners. Given the global contamination of PBDE in marine sediment, BDE 47 may potentially alter the settlement pattern of marine polychaetes and hence their benthic composition over large areas. Copyright © 2010 American Chemical Society.