Effects of zinc (Zn) and copper (Cu) on cadmium (Cd) accumulation were investigated in LLC-PK1 cells. Coincubation with Zn or Cu decreased Cd uptake by the cells in a concentration-dependent manner. Cd accumulation data suggested that Cd is taken up by the cells via simple diffusion and carrier-mediated transport. Zn and Cu significantly increased the Km of Cd uptake with no or little effect on the Vmax. Pretreatment of the cells with ouabain and a metabolic inhibitor (FCCP) significantly decreased Cd accumulation, and coincubation with Zn or Cu led to an additional decrease in Cd accumulation by these cells. Overall, it seems that, in addition to simple diffusion, Cd is also taken up by LLC-PK1 cells via carrier-mediated mechanisms that are competitively inhibited by Zn and Cu.