The partitioning of C-14-labelled 2,2',4,4'-tetrachlorobiphenyl (TCB) between fish lipids and water was studied in a continuous flow system. Fish lipids with high phospholipid content (>20% by weight) accumulated significantly less TCB than did fish lipids with low phospholipid content (<10% by weight). The results suggest that the bioconcentration factor of a hydrophobic compound is species specific depending on lipid composition.