A PACS prototype has been installed and evaluated at the University of Washington. This paper presents the work done in the performance evaluation of the PACS prototype. The work involved network and workstation performance measurements and development of a simulation model based on the performance measurements. The simulation model was then used to do a parametric study of the PACS prototype to pinpoint the bottlenecks and suggest corrective measures. Results show that there are some local bottlenecks in the PACS prototype and an overall global bottleneck in the Data Management System (DM5) which forms the hub of the PACS prototype.