We applied a bioenergetic model to describe uptake of polychlorinated biphenyls (PCBs) by lake trout (Salvelinus namaycush), brown trout (Salmo trutta), lake whitefish (Coregonus clupeaformis), coho salmon (Oncorhynchus kisutch), and chinook salmon (Oncorhynchus tshawytscha) in Lake Michigan; lake trout and lake whitefish in Green Bay of Lake Michigan; and lake trout in Cayuga Lake, New York. The model describes PCB uptake in terms of metabolism, food consumption, size, and growth. Concentrations of PCBs differ significantly among species; for the same species there are large differences among habitats. The pattern of PCB uptake by brown trout is different from that of the other species. Application of the model with uptake and metabolic parameters estimated by Norstrom et al. describes the trend in the brown trout data; to describe uptake for other species we increased the exponent of weight for metabolism γ. An increase in γ changes the shape of the relation between PCB concentration and body weight from asymptotic to non-asymptotic. In all species tested except brown trout, uptake of PCBs was not asymptotic and concentrations did not approach an equilibrium; accumulation of contaminants was first rapid, decreased toward a plateau, and then began a second rapid increase. Simulation studies indicate that differences in PCB concentrations among species and in the same species among different environments result from differences in metabolic parameters, exposure, size, and rate of growth.Key words: PCBs, bioenergetic model, contaminant uptake, toxicology, fish, Great Lakes, salmon, trout, whitefish