We investigated regional cerebral blood flow (rCBF) patterns in Binswanger's disease (BD) patients using single photon emission computed tomography (SPECT). SPECT data on 22 patients with BD were analyzed using three-dimensional stereotactic surface projections (3D-SSP) and were compared with those of 22 patients with Alzheimer's disease (AD). rCBF patterns in patients with BD were different from those with AD. The BD group had greater CBF reduction in the frontal and anterior cingulate cortices, while the AD group had greater CBF reduction in the temporoparietal and posterior cingulate cortices. However, the rCBF pattern of each patient was more variable, and could be divided into three patterns: anterior cerebral hypoperfusion, posterior cerebral hypoperfusion, and diffuse cerebral hypoperfusion patterns. A distinct CBF reduction in the temporoparietal and/or posterior cingulate cortices, indistinguishable from the CBF pattern observed in AD, was demonstrated in 8 of 22 (36%) patients with BD, in particular there was bilateral hemispheric involvement with a diffuse hypoperfusion pattern. Although no pathological confirmation could be performed, some of the BD patients with CBF reduction in the posterior cerebral cortices may represent additional changes in the brain due to AD. In the future, a longitudinal study including pathology will be needed to determine whether these patients have coexisting AD pathology.