This paper describes VolumePro, the world´s first single-chip real-time volume rendering system for PC class computers. VolumePro implements object-space ray-casting with parallel slice-byslice processing. Our discussion of the architecture focuses on the rendering pipeline, the memory organization, and sectioning, which is a data partitioning scheme to reduce on-chip buffer requirements. We describe several advanced features of VolumePro, such as gradient magnitude modulation of opacity and illumination, supersampling, supervolumes, and crop and cut planes. The system renders more than 500 million interpolated, Phong illuminated, composited samples per second. This is sufficient to render a 256 x 256 x 256 volume at 30 frames per second.