Technical Abstract: Polybrominated diphenyl ether (PBDE) mixtures are manufactured as flame retardant additives for electronic equipment, plastics and textiles. PBDEs are ubiquitous environmental contaminants, their bioaccumulation has led to the detection of PBDEs in many species of wildlife, human blood plasma and in milk. PBDEs are structurally similar to polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs), and thyroid hormones, and therefore may interfere with thyroid hormone homeostasis. Because of their potential health consequences it is desirable to have a rapid and high throughput assay to monitor PBDEs. Enzyme immunoassays (ELISAs), have proven to be rapid, sensitive, accurate, and cost-effective. Magnetic particle-based ELISAs have previously been described and widely applied to the detection of pesticides and other environmental contaminants in various sample matrices, including water, soil, produce, and fish tissue. The uniform dispersion of the particles throughout the reaction mixture allows for rapid reaction kinetics, precise addition of antibody and superior analytical sensitivity. This paper describes the development and assay performance of a magnetic particle-based ELISA for PBDEs in whole fish samples. The results showed that the magnetic particle based ELISA and GC-MS values are comparable with r2 = 0.872 at a measured range of 50 to 4800 ppt in 18 samples. Future plans include applying this assay method to soil, sediment and waste water samples and validating the results with GC-MS.