The expression and inducibility of cytochrome P450 proteins belonging to families CYP2, CYP3 and CYP4 in the aorta of rabbits were investigated immunologically using polyclonal antibodies to the hepatic proteins. Antibodies to CYP2B recognised two proteins, only one of which was inducible by phenobarbitone. One protein was detected by anti-CYP2E1 which was modestly inducible by imidazole. A highly expressed protein was recognised by antibodies to CYP3A1, the levels of which diminished following treatment with rifampicin. Finally, antibodies to CYP4A1 immunoreacted with a single protein in the aorta which was refractive to treatment with ciprofibrate. The data demonstrate that the rabbit aorta expresses a number of cytochrome P450 families which, although inducible in the liver, are not always inducible in the aorta.