Cerebral ischaemia caused by inflammatory vasculopathies has been described as complication of human immunodeficiency virus (HIV) infection. Imaging studies have shown ischaemic lesions and changes of the vascular lumen, but did not allow demonstration of abnormalities within the vessel wall itself. Two HIV-infected men presented with symptoms of a transient ischaemic attack. Initial MRI of the first showed no infarct; in the second two small lacunar lesions were detected. In both cases, multiplanar 3-mm slice contrast-enhanced T1-weighted images showed aneurysmal dilatation, with thickening and contrast enhancement of the wall of the internal carotid and middle cerebral (MCA) arteries. These findings were interpreted as indicating cerebral vasculitis. In the first patient the vasculopathy progressed to carotid artery occlusion, and he developed an infarct in the MCA territory, but then remained neurologically stable. In the second patient varicella zoster virus (VZV) infection was the probable cause of vasculitis. The clinical deficits and vasculitic MRI changes regressed with antiviral and immunosuppressive therapy.