This paper briefly describes several research projects at UNC Chapel Hill involved with the display of 3D medical image data. A number of display methods is reviewed, and several new approaches outlined. Despite dramatic progress in display capability in recent years, even the most powerful current systems are inadequate for many daily medical imaging tasks. More powerful display systems in the near future may dramatically increase comprehensibility of complex 3D medical image data by enabling smooth interaction by direct manipulation, display without noticeable lag, and presentation of more powerful 3D depth cues such as head-motion parallax and stereopsis. These new systems will consist not only of a more powerful display engine, but also of an improved user interface with which the user can more easily interact than with current systems. One promising such interface for the future is based on a head-mounted display, one that allows the user to observe synthetic 3D structures superimposed on the world around him, allowing him to walk about these structures and modify them by direct manipulation using hand-held (simulated) tools. The poor quality of current miniature video displays prevents this approach from becoming a useful display method for 3D medical image data.