This study investigated the sublethal effects of CdSO4 on the terrestrial isopod species Porcellio laevis and its capacity to accumulate and compartmentalize cadmium. The ability of P. laevis to discriminate between uncontaminated and CdSO4-contaminated leaves was also studied. It was shown that sublethal effects in terms of mass changes of exposed isopods occur at cadmium concentrations between 10 and 80 mg/kg. Moreover, P. laevis can be considered as a so-called macroconcentrator, accumulating and storing cadmium in its hepatopancreas tissue. However, the accumulation capacity is not proportional to the cadmium concentrations in the leaves presented as food, as shown by decreasing concentration factors with increasing cadmium concentrations in the diet. This is probably an effect of the isopod's ability to discriminate between different cadmium concentrations in the food, as shown by means of feed-choice experiments, in which P. laevis was able to avoid contaminated leaves.