Haloperidol is a widely used antipsychotic drug, which exerts its effects via antagonizing the dopaminergic D2 receptors. Also it affects a number of receptors on vascular bed and other tissues. The impact of haloperidol on vascular bed seems still debatable and not clear. In the present study, haloperidol was given to adult rats in 0.5, 1, 2.5 and 5 mg kg(-1) doses, once a day, intraperitoneally in I ml volumes, for 9 weeks. After decapitation under Pentothal anesthesia, brains and basilar arteries were dissected out at midpontine level immediately. Conventional histopathology and morphometric analysis were carried out on the dissected artery branches.