This report describes a method for measuring regional cerebral blood volume (r-CBV), by simultaneously using dynamic computerized tomography (DCT) and stable Xenon-enhanced CT (Xe CT). Local cerebral blood flow (CBF) was measured using a Xe CT blood sampling method, and mean transit time (MTT) was calculated using DCT after a rapid injection of iodinated contrast material. A functional image of r-CBV was obtained from multiplication of CBF and MTT on each pixel using the formula: CBF x MTT = CBV. This calculated value is not suitable to indicate a r-CBV which directly reflects cerebral microcirculation. Accordingly, only a comparative estimation of relative r-CBV images is applicable. However, laterality of image and comparison of serial studies are useful in hemodynamic evaluations, especially in ischemic cerebrovascular diseases, because they indicate hemodynamic reserve within the hypoperfused region.