Adults ofPomphorhynchus laevis andAcanthocephalus lucii were analyzed for cadmium by atomic absorption spectrometry Their cadmium concentrations were compared with those found in different tissues (muscle, liver, and intestine) of their final hosts the chub and perch. Additionally, the cadmium and lead concentrations in larvae ofA. lucii and their intermediate hostAsellus aquaticus were determined. Regarding the adult acanthocephalans, the parasites showed several times more cadmium than did the tissues of their fish hosts. In contrast to this obvious accumulation capacity of adultA. lucii, the larvae contained less cadmium than did their crustacean host. Thus, the cadmium concentration in the larval stages was nearly 180 times lower than that measured in the adult worms. According to the present results, it appears that the heavy metals cadmium and lead are predominantly accumulated by the adult acanthocephalans inside the fish gut and not by the larvae inside the hemocoel of the crustaceans.