A one-step extraction and clean-up step, followed by derivatization of the extracts, was developed for the simultaneous analysis of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and their hydroxylated metabolites in fish using gas chromatography/mass spectrometry (GC/MS). Twenty one common carp (Cyprinus carpio) were collected from Lake Erie in Dunkirk Harbor (NY) over a two week period in early May 2006. Fish tissue, liver, and plasma were extracted using accelerated solvent extraction and then derivatized for GC/MS analysis. Aliquots of tissue and plasma extracts were also analyzed using a competitive enzyme-linked immunosorbent assay (ELISA) for PBDE. Furthermore, plasma samples were analyzed for vitellogenin (VTG), a biomarker for endocrine disruption in fish, by sandwich ELISA. Total PCB concentrations ranged from 8.30 to 1131.06 ng/mL in tissue. Total PBDE concentrations, in tissue and plasma, ranged from 2.55 to 45.55 ng/mL. VTG concentrations in plasma from 18 male carp ranged from 0.14 to 230.35 ng/mL. Of the 12 male carp with elevated VTG, 8 showed upper ng/mL levels of total PCBs and PBDEs, however no linear correlation between increased VTG levels and high PCB and PBDE concentrations could be made. PCB and PBDE metabolite concentrations fell below the limits of detection. Twelve of the 18 male carp showed elevated VTG levels indicating endocrine disruption in the carp population in Lake Erie.