Concentrations of seven metals (Cr, Ni, Cu, Zn, Cd, Hg, and Pb) and a range of organochlorine pesticides, individual chlorobiphenyl congeners, and total polychlorinated biphenyls (PCB) have been determined in tissues of dolphins, porpoises, seals, and a variety of food chain species and sediments from Cardigan Bay, West Wales. Elevated concentrations of metals were not seen in any of the animal tissues examined. Higher than expected levels of organochlorine compounds were found in tissues of dolphins and porpoises; these concentrations are not derived from local pollution, but come from the animals' normal diet which did not show markedly elevated levels of organochlorines. The level of organochlorine bioaccumulation seen in some of the cetaceans analysed is much higher than found previously; this may have serious health implications for populations of those species around the coasts of NW Europe.