Abstract. Streaming media workloads have a number of desirable properties that make them good candidates for caching via proxy systems. The content does not get modified, and access patterns exhibit some locality of reference. However, media files tend to be much larger in size than traditional web pages, and users tend to view video clips only partially. Hence, segment-based strategies have been proposed to deliver large streaming media objects via a web-proxy. In this work, we evaluate the performance of such a segment-based streaming proxy using extensive trace driven simulation. We use representative workloads from enterprise media server logs, and evaluate the caching system performance regarding different cache sizes, different segment sizes, and different prefetching methods. Our results show that cost-effective caching requires only about 8 - 16 % of the total unique object size as proxy storage. Secondly, a segment size of around 200 Kbytes provides a good trade-off bet...