Twenty patients with strokes were studied to evaluate volume and surface three-dimensional (3D) displays in Tc-99m HMPAO brain SPECT imaging using a triplehead gamma camera interfaced with a 64-bit super computer. In each patient, after an intravenous injection of 20 to 30 mCi of Tc-99m HMPAO, a first-pass cerebral flow study and brain SPECT images at 30 to 60 minutes were obtained. Although the cerebral lesion was more clearly delineated with surface 3D and volume 3D, crossed cerebellar diaschisis in seven patients was more clearly exhibited by volume 3D rather than surface 3D imaging. Volume and surface 3D displays enhance continuity of structures and understanding of spatial relationships; these displays view the brain from all angles, and thus the location and extension of lesion(s) in the brain are much easier to appreciate. It is concluded that 1) both surface and volume 3D displays equally enhance SPECT interpretation; and 2) volume 3D display enhances demonstration of crossed cerebellar diaschisis, but surface 3D display does not.