At the University of Arizona, software development for image viewing tasks use object-oriented techniques for scalability, portability, cost and the ability to adapt rapidly to changing technology. Object orientation facilitates object-based decomposition, rapid development, code reuse and portability. These techniques were used developing software for a diagnostic system for the Pulmonary Section of Toshiba General Hospital, Tokyo, Japan. Object-oriented analysis and design were based on the Grady Booch method. Implemented used visual C++. Software components are implemented as cooperating objects. The resulting Toshiba-Arizona Viewing Station (TAVS) software system was installed in Tokyo in July 1996 for clinical evaluation. The host system provides 1760 X 2140, grey scale resolution. HIS/RIS integration allows HIS/RIS workstations to control the TAVS. TAVS code has been demonstrated on systems ranging from 'palm-top' computers to high-performance desktop systems. TAVS software objects were then modified and a TAVS system was installed in the University Medical Center, Tucson, Arizona supporting diagnostic image viewing tasks in the Emergency Department. This approach has demonstrated support for rapid development and adaptability to diverse end-user requirements and produced software which can operate across platforms.