An image analysis system was developed for stereotactic neurosurgery that allows the simultaneous display of brain images from different imaging devices obtained in different orientations. The system is based on a stereotactic frame and a microcomputer and features an easy user interface together with point registration and region of interest analysis in three-dimensional space. A dynamic multi-image environment allows for simultaneous display of magnetic resonance, computed tomography, digital subtraction angiography, and positron emission tomography images in multiple windows, adjusted for common coordinates with reference to stereotactic frame fiducial markers. Linkages between images allow information interchange between different modalities and different views: Points and regions defined in one image can be transferred to others, and cursor coordinates in one image can be calculated and dynamically projected in other images. Phantom studies show that the system distortions are minor and that the system is suitable for clinical use. The system provides exceptional advantages over previous imaging procedures for stereotactic surgery.