CYP1B1, a new member of human cytochrome P450 family 1, is involved in the xenobiotic detoxification metabolism and possibly activation of numerous procarcinogens and promutagens. Localization of CYP1B1 in human temporal lobe and its induction in astrocytoma cell line (MOG-G-CCM) by 7,12-dimethylbenz(a)anthracene (DMBA) was investigated using antibodies against human CYP1B1. A single band of approximately 58 kDa size in both human temporal lobe and in MOG-G-CCM was detected by Western blot analysis. Treatment of MOG-G-CCM cells with DMBA resulted in approximately 2.8-fold induction of CYP1B1. CYP1B1 immunoreactivity was detected at the blood-brain interface areas of the temporal lobe as evidenced by co-localization with CD34 antigen. These results suggest that this enzyme may be important in brain xenobiotic metabolism acting as an enzymatic barrier.