Local cerebral blood flow (LCBF) and local tissue: blood partition coefficient (L lambda) values were measured for small volumes of gray or white matter by CT CBF. Single compartment analysis was used but fitted to infinity in normal volunteers aged between 20 to 100 years (N = 20). Hemispheric LCBF and L lambda values were compared to those of 61 age matched patients with transient ischemic attacks (TIAs, N = 10), reversible ischemic neurologic deficits (RINDS, N = 10), acute and chronic cerebral infarctions associated with emboli from atherosclerotic plaques or complete occlusion of internal carotid or middle cerebral arteries (n = 9) or of cardiac origin (N = 3), cerebral hemorrhage (N = 1), multi-infarct dementia (MID) (N = 11) and arteriovenous malformations (AVM) (N = 17). In normal aging, L lambda s were normal, but LCBF showed diffuse age-related declines. Symptomatic cerebrovascular disease was characterized by accentuation of age-related LCBF declines. TIAs with unilateral ICA occlusion showed bilateral reductions of LCBF more evident in ischemic hemispheres. TIAs due to fibrino-platelet emboli from ulcerated, non-occlusive ICA plaques were characterized by transient unilateral, localized LCBF reductions. All TIAs showed normal L lambda values. RINDS showed both LCBF and L lambda reductions. Larger embolic infarctions of ICA origin, whether acute or chronic, showed zones of zero flow with surrounding reductions of LCBF and L lambda values. Recent cerebral embolism of cardiac origin likewise exhibited zones of zero flow surrounded by reduced LCBF and L lambda values; but in chronic stages LCBF and L lambda values adjacent to zero flow zones were normal. MID was characterized by patchy reductions of LCBF and L lambda values throughout both hemispheres. Brain tissues surrounding AVM showed normal L lambda values but LCBF values were reduced due to steal.