To explore the levels of polybrominated diphenyl ethers (PBDEs) in California, samples from 11 archived harbor seals (Phoca vitulina Richardsi) from the San Francisco Bay and breast adipose tissue samples from 23 women were analyzed. The levels of PBDEs in human tissue samples were in the low ng/g fat range, with PBDEs 47, 153, 154, 99, and 100 as the major congeners. Average sigma PBDEs (86 ng/g fat) in these California women are the highest human levels reported to date. An inverse relationship between concentration of PBDEs and age of these women was apparent. The levels of PBDEs measured in harbor seal blubber were in the low ng/g to low microg/g fat range, with the same major congeners as those measured in the human tissues. PBDE 47 was the highest among all congeners measured in both human tissue and seal blubber samples. The concentrations of PBDEs in harbor seals in the San Francisco Bay have increased dramatically over the past decade, with current levels among the highest reported for this species.