This paper initially describes the functional specifications of a generic digital workstation for medical images. These generic specifications have formed the basis of a first generation PACS design currently in clinical evaluation. Preliminary observations of the first generation system in a clinical environment suggests an oppor-tunity to optimize both performance and cost effectiveness. Functional specifications are presented for a series of workstations specializing in four major applications, Image Acquisition, Image Review, Image Processing, and Image Archiving. The tmportance of performance and the impact of system architecture on the individual workstation specifications will be clearly noted. The relative composition of hardware and software specialization in each workstation design will also be described. The specification of a useful multimodality workstation is therefore largely determined by application and performance expectations and significantly influenced by the particular system architecture chosen.