A network of hospitals is planned that will be able to share radiology services. The hospitals and clinics involved will be related in four different ways: (1) Outlying clinics using a hospital radiology service; (2) Multiple cooperating radiology services with one administration; (3) Multiple cooperating radiology services with separate administrations; (4) Shared archive services on the network. The expected operation in each of the scenarios is discussed including an estimate of the amount of shared traffic between the providers. The services provided by a single administration will result in the largest sharing of radiology exams and the greatest utilization of the communication network. Separate administrations are expected to share patients and exams much less frequently. The network archive can be used to reduce the cost of an installation with somewhat reduced archive performance. The sharing of services is facilitated by an effective interaction between the separate imaging systems. A shared administration means that one database can be used to organize data flow and workflow around the hospitals. The interaction of two databases when there are two separate administrations changes the level of cooperation that is possible. A distributed PACS will be installed in several hospitals: clinics associated with the DeWitt Hospital at Ft. Belvoir, Virginia; The DeWitt Army Hospital at Ft. Belvoir, Virginia; Walter Reed Army Medical Center, Bethesda, Maryland; National Naval Medical Center, Bethesda, Maryland. DeWitt, its clinics and Walter Reed Army Medical Center are under one administration. The National Naval Medical Center is under a separate administration. The ability to cooperate in providing radiology services across these institutions will be established and the level of sharing across the institutions will be measured. The archive node will provide archive services for those hospitals without an archive, will provide archive services for those radiological exams that are older than are retained on local archives, and will provide a backup archive in case of catastrophic failure at a hospital.