The possibility of a central component in the cardiovascular effects of peripherally administered calcium channel blockers has been explored through a comparison of the effects observed after intravenous (i.v.) and intracisternal (i.c.) administration of verapamil and diltiazem in chloralose-anesthetized and artificially ventilated cats. Both agents produced relatively greater effects after i.c. than after i.v. administration. The bradycardiac effect following i.c. as well as i.v. administration was totally abolished by bilateral cervical vagotomy, and the hypotensive effect was attenuated by this procedure. The results strongly suggest the existence of a central component in the cardiovascular effects of both agents.