A method for computed tomography (CT)-based stereotactic biopsy of intracranial neoplasms with arteriographic control is described. Stereotactic CT and digitized stereotactic arteriographic data are input to a three-dimensional computer matrix that corresponds to the coordinate system of a stereotactic frame located in the operating room. A site for biopsy is selected by cursor from the CT display screen. The computer calculates and outputs the mechanical adjustments of the stereotactic frame necessary to place the target point into the focal point of the frame. Horizontal and vertical approach angles are determined from the digitized arteriogram and are displayed as settings on the stereotactic frame that represent an avascular trajectory along which the lesion may be biopsied safely. This procedure has been used successfully in 86 patients, with no morbidity or mortality.