A mathematical model of the transfer of PCBs through the freshwater aquatic food chain is described. The model predicts concentrations of 11 selected individual PCB congeners in forage fish and pike, from source terms of atmospheric deposition and watershed soil concentrations. Model performance has been evaluated using data from a field study conducted in a section of the River Severn near Birmingham, UK. Results demonstrate that with the exception of congener 52, overall model predictions of individual PCB concentrations in both forage fish and pike underestimate measured concentrations by factors of between approximately 3 and 25 for individual congeners. Closer examination suggests that whilst model equations contribute to these underestimations, a significant factor is the lack of knowledge of additional PCB inputs to the waterbody.