The effects of copper, cadmium and lead on the bioaccumulation of zinc were studied in populations of the gastropod mollusc Littorina saxatilis from sites in the Isle of Man subjected to varying degrees of mine-related metal contamination. Exposures to 2 mg/L Zn alone and in combinations with 0.01 mg/L, 0.1 mg/L and 1 mg/L of the respective metals were conducted at ∼10 ∘C in semi-static assays. Copper had a significant antagonistic effect on Zn accumulation at 1 mg/L Cu, but was not antagonistic at 0.01 and 0.1 mg/L Cu. Prior exposure to metals in the field did not appear to affect the interactive effect of copper as all populations showed similar patterns. Combinations of Zn with Cd or Pb at the above concentrations did not show any significant effects on Zn accumulation. On the other hand, Zn had an antagonistic effect on Cd and Pb accumulation but showed inconsistent effects on Cu accumulation. Interactions of Cu and Zn in particular may have repercussions for interpretation of biomonitoring data in L. saxatilis.