A rendering technique for interactive direct volume visualization on mobile devices is presented. Utilizing basic graphics hardware functionality such as rasterization and 2D texture mapping, native volume rendering is possible by adopting and extending the 2D texture-slicing approach. Limitations of mobile graphics devices are discussedœôòôin particular concerning graphics performance and available functionality. These limitations lead to modifications of the traditional texture-based volumerendering algorithm: we propose a screen-adaptive hybrid low/high-resolution rendering technique that achieves a good compromise between image quality and interactivity; furthermore, compressed and paletted texture formats are explored for fast texture update, for example, during interactive specification of the transfer function. The implementation of the rendering algorithm is based on OpenGL ES 1.0 and was tested on the Dell Axim X50v/X51v PDA. Performance characteristics are documented in the form of several kinds of performance measurements.