Remote data exchange is extremely useful to a number of medical applications. It requires an infrastructure including systems, network and software tools. With such an infrastructure, existing local applications can be extended to serve national needs. There are many approaches to providing remote data exchange. Selection of an approach for an application requires balancing of various factors, including the need for rapid interactive access to data and ad hoc queries, the adequacy of access to predefined data sets, the need for an integrated view of the data, the ability to provide adequate security protection, the amount of data required, and the time frame in which data is required. The applications described here demonstrate new ways that the VA is reaping benefits from its infrastructure and its compatible integrated hospital information systems located at its facilities. The needs that have been met are also needs of private hospitals. However, in many cases the infrastructure to allow data exchange is not present. The VA's experiences may serve to establish the benefits that can be obtained by all hospitals.