Hydroxylated metabolites of polychlorinated biphenyls (HO-PCBs) have previously been associated with endocrine disrupting effects. Since metabolic capacity may differ among species, we investigated the levels and profiles of HO-PCBs and PCBs in livers of four predatory bird species from Belgium. Maximum concentrations for sum HO-PCBs were found in the common buzzard (Buteo buteo) up to 13 700 pg/g wet weight (ww). The most prominent HO-PCB congener in all bird species was 4-HO-CB 187 (up to 6420 pg/g ww in buzzard liver), followed by 4-HO-CB148 in the buzzard (up to 1820 pg/g ww), sparrowhawk (Accipiter nisus), and grey heron (Ardea cinerea), and by 3'-HO-CB138 in long eared owl (Asio otus) and in one grey heron (up to 985 pg/g ww and 3450 pg/g ww, respectively). The mean profile of the grey heron differed from the other species with 3'-HO-CB138 and 4-HO-CB163 contributing more to the sum HO-PCBs. This indicates that aquatic and terrestrial predatory bird species may show differences in their HO-PCBs profiles. Variation in the diet and species-specific accumulation and metabolism of PCBs are probably the most important causes for these differences. Correlations between HO-PCBs and their parent PCBs were only found significant for buzzards.