This study was designed to determine whether neuroleptic drugs have calcium channel blocking activity in isolated rings of rabbit thoracic aorta. The results confirm previous findings that pimozide and penfluridol are calcium channel blockers. However, the data do not support the conclusion that these agents are selective for the voltage-sensitive calcium channel. The results also show that both haloperidol and chlorpromazine (which represent different classes of neuroleptic drugs) are also calcium channel blockers in vascular smooth muscle.