Polybrominated diphenyl ethers (PBDEs) used to prevent fire are found in several products, such as textiles, electronics, and building materials. They are lipophilic and persistent substances, and their toxicological endpoints resemble those of polychlorinated bipenyls (PCBs). One of the most abundant congeners of PBDEs in wildlife is the 2,2',4,4',5-pentabromodiphenyl ether (PBDE-99). To study the effect of PBDE-99 on vitamin status in birds and evaluate the possible application of vitamins as biomarkers for use in monitoring of wildlife, eggs of domestic duck (Anas platyrhynchos) were exposed by yolk sac injection to environmental realistic doses of this congener (0.1, 1, or 10 ng/g ww). Levels of retinol (vitamin A), retinyl palmitate, and -tocopherol (vitamin E) were measured in the liver of the newly hatched chicks, and levels of retinol and tocopherol were also measured in plasma. Liver tocopherol levels correlated negatively to the exposure to PBDE-99. This is an indication that exposure to PBDE-99 reduces levels of tocopherol in liver. Thus, tocopherol seems to be a potential useful biomarker for exposure to PBDEs in bird species.