The shore clam Ruditapes philippinarum was used as a biomonitoring organism to measure the potential impact that the mining spill in the Guadalquivir Estuary (SW, Spain) in 1998 may have exerted on local biota. Individuals were exposed to dissolved cadmium, copper, and zinc at concentrations found in local waters after the spill (3 microg x L(-1) Cd, 15 microg x L(-1) Cu, 700 microg x L(-1) Zn) at two salinity values: 10 and 35. Residues of metals were measured in gill and digestive gland, together with metallothioneins in the digestive gland and histopathological lesions in gill, digestive gland, and gonad tissues over time. Heavy metals Zn and Cd associated with the mining spill, were bioaccumulated in clam tissues, associated with the activation of metallothioneins, and related to the histopathological lesions measured at all the clam tissues. The heavy metal Cu not related to the spill was not directly associated with effects measured. The bioaccumulation and adverse effects associated with Cd and Zn were significantly higher at low salinity (10) than at high salinity (35) values.