Although caching and the creation of cache server hierarchies has became a popular strategy for reducing user waiting time and network traffic, there is no recipe for determining the best hierarchy configuration given a set of machines and the workload that they have to serve.This paper presents a novel approach for analyzing the performance of cache proxy hierarchies that is based on two metrics: hierarchical hit ratio and cache efficiency. This approach allows users to easily quantify trade-offs among configurations, facilitating the tuning of cache hierarchies. We illustrate our approach by analyzing possible configurations for a proxy server.