The Medical Image Processing Group (MIPG) at the University of Pennsylvania has been developing and distributing medical image analysis and visualization software systems for a long period of time. Our most recent system, 3DVIEWNIX, was first released in 1993. Since that time, a number of significant advancements have taken place with regard to computer platforms and operating systems, networking capability, the rise of parallel processing standards, and the development of open source toolkits. The development of CAVASS by our group is the next generation of 3DVIEWNIX. CAVASS will be freely available, open source, and is integrated with toolkits such as ITK and VTK. CAVASS runs on Windows, Unix, and Linux but shares a single code base. Rather than requiring expensive multiprocessor systems, it seamlessly provides for parallel processing via inexpensive COWs (Cluster of Workstations) for more time consuming algorithms. Most importantly, CAVASS is directed at the visualization, processing, and analysis of medical imagery, so support for 3D and higher dimensional medical image data and the efficient implementation of algorithms is given paramount importance. This paper focuses on aspects of visualization. All of the most of the popular modes of visualization including various 2D slice modes, reslicing, MIP, surface rendering, volume rendering, and animation are incorporated into CAVASS.