Dynamic contrast-enhanced T2-weighted magnetic resonance (MR) imaging and MR angiography (MRA) were used to evaluate cerebral blood volume and the intracranial arterial system in 34 patients within 48 hours after the onset of cerebral ischemia. In 24 of the patients, an abnormality identified on T2-weighted images corresponded to the acute clinical deficit. Intracranial MRA demonstrated occlusions or severe stenoses of major vessels supplying the area of infarction in 16 of these patients, and decreased blood volume correlated well with MRA abnormalities. Infarcts less than 2 cm in diameter were not reliably shown with MRA or blood volume studies. Correlation between lesions seen with MRA and decreased blood volume in acute infarcts was good, and both techniques demonstrated lesions early in the clinical course. By providing information about hemodynamics not available with conventional T1- or T2-weighted images, MRA and dynamic MR imaging could prove helpful in describing the pathophysiologic characteristics of stroke and in guiding early therapeutic intervention.