Research into all aspects of PACS increased in the 1980s as advances in technology enabled key components of PACS to be implemented. The University of Washington has worked on many issues of PACS, such as workstation development, teleradiology, and PACS-RIS (Radiology Information System) interconnection. In the past, special-purpose workstations have had to be developed to support the high demands of medical imaging. However, recently developed general-purpose workstations are now being considered as potential components of a PACS. Our latest research, a joint UW/IBM study, has involved the development of a system based on the IBM RISC System 6000 (RS6000). Evaluations of radiology workstation user interfaces led to the conclusion that a Graphical User Interface is the most acceptable. Since a general-purpose workstation is employed, it was felt that the software should be as portable as possible. These two requirements led to the selection of the X Window System for software development. What is discussed in this paper is the development of image display and processing functions on the RS6000 in the X Window System environment, and how this development effort satisfies the requirements of a PACS workstation.