Abstract: VIRIM, a real-time direct volume rendering system is evaluated for medical applications. Experiences concerning the hardware architecture are discussed. The issues are the flexibility of VIRIM, the restriction to two gradient components only, the duplication of the volume data sets on different modules, the size of the volume data set, the gray-value segmentation tool, and the support of algorithmic improvements like space- leaping, early ray-termination and others.It turned out that flexibility is the main benefit and absolutely necessary for VIRIM. Given this flexibility the application areas of real-time rendering systems increase dramatically: Most of the user requirements focus now not on visualization but on general volume data processing. The most serious bottleneck of VIRIM is the limited volume memory that is integrated on the first prototype.