The concentrations of As, Cd, Hg, Pb and Zn have been determined in oysters and sediments from the Lynher Estuary, U.K. The sediments contained high levels of Cu, Fe, Pb and Zn probably associated with run off from a metalliferous catchment area and high Hg associated with a local sewage input. In contrast, the analyses of the oyster tissue showed that only Cu and Zn were concentrated in the flesh. The majority of samples contained coliform bacteria in excess of 1000 organisms per ml of tissue. It is concluded that the quality of the oysters from this fishery was limited by the bacteriological cleanliness rather than toxic metal content.