Abstract:The concentration of ten kinds of polychlorinated biphenyls in body fat of five East Asian finless porpoise(Neophocaena asiaeorientalis sunameri) and three Yangtze finless porpoise(Neophocaena asiaeorientalis asiaeorientalis) in Yangtze River Estuary were measured by gas chromatograph-mass spectrometer (GC-MS). The result shows that, the average content of PCBs in Narrow-Ridged finless porpoise in Yangtze River Estuary was 3.38 μg/g, wet weight. The content of PCBs in Yangtze finless porpoise(3.4-12.67μg/g) was significant higher than that in East Asian finless porpoise(0.33-2.21μg/g) (P < 0.05). In these ten kinds of polychlorinated biphenyls, monochlorobiphenyl, dichlorobiphenyl, trichlorobiphenyl were not detected in every individual finless porpoise(<0.005μg/g),and tetrachlorobiphenyl, pentachlorobiphenyl, hexachlorobiphenyl, heptachlorobiphenyl were all detected in every individual finless porpoise. The average content of hexachlorobiphenyl was 1.48μg/g wet weight, accounting for 43.79% of the total PCBs content. From the composition of PCBs content, the percentage of hexachlorobiphenyl and heptachlorobiphenyl were higher than other chlorinated PCBs in Narrow-Ridged finless porpoise in Yangtze River Estuary. But compared with East Asian finless porpoise, the content of tetrachlorobiphenyl and pentachlorobiphenyl in Yangtze finless porpoise also account for high proportion. This suggests that low chlorinated component of PCBs can be degraded with water dilution and biological transformation, but high chlorinated component of PCBs is not easy to degrade. With the growth of finless porpoise age, high chlorinated component of PCBs in finless porpoise accumulate fast, it will have a more lasting toxicity effect.