Estuarine sediment containing high levels of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) was resuspended into a flowing seawater system. Analysis of the dissolved and particulate phases in the exposure tank indicated a release of some low molecular weight PCB and PAH compounds from the sediment. Both classes of compounds were rapidly incorporated by blue mussels, Mytilus edulis maintained in the system, reaching an apparent equilibrium concentration after twenty days of exposure. The distribution of both classes of compounds accumulated in the mussels suggested selective absorption of specific fractions.