Most CYP subfamilies have been identified in brain, but there is much more information available on the distribution and metabolic activity of CYP subfamilies in brain of rodents than in humans, and what we do know still lags far behind our knowledge of hepatic CYPs. With the constant acquisition of data on the genetics, molecular structure and metabolic capacity of brain CYPs, we are increasingly able to investigate their role in the brain and the possible consequences of altered local metabolism. However, at this stage, the contribution of brain CYPs to local metabolism of drugs, toxins and endogenous compounds is still speculative, as is the role for these CYPs in modulating brain function and in the development of brain diseases. Much investigative work remains to be done to firmly establish the links between the presence of CYPs in brain, their function in this highly heterogeneous and complex organ and the consequences on overall brain function and health.