||The contamination of the Gironde Estuary, southwest of France, by polychlorinated biphenyls (PCBs) was assessed using six fish of high ecological and economic importance as bioindicator species. The concentrations of 21 PCB congeners and total fat contents were determined in the muscle and liver of eels (Anguilla anguilla), seabass (Dicentrarchus labrax), flounders (Platichthys flesus), meagres (Argyrosomus regius), mullets (Liza ramada), and soles (Solea vulgaris). In addition, information regarding the trophic ecology of the studied fish was obtained through the analysis of carbon and nitrogen stable isotopes (i.e., delta C-13 and delta N-15) in muscle. Results revealed high PCB concentrations in fish compared to monitored European estuaries. The muscle of eels was by far the most contaminated fish flesh (Sigma(7)PCBs = 1000 +/- 440 ng g(-1), on a dry weight basis), while the higher PCB concentrations in liver were measured in flounder (Sigma(7)PCBs = 2040 +/- 1160 ng g(-1), d.w.). A quantile regression approach allowed to investigate the fate of PCBs in the Gironde estuarine fish assemblage, and revealed a general process of trophic magnification. Finally, most of the analysed fish presented PCB concentrations in muscle meat above the current European maximum limits for sea products, while the derived “Toxic Equivalent Quantity” (TEQ) revealed human health concerns only for high-fat fish consumption.