Methods for supplying medical personnel, especially in isolated areas, with the same sophisticated medical information and computational facilities that are available in major medical centers, were investigated. Inexpensive, readily available input/output terminals, including the pushbutton telephone, were tested with several biomedical application programs. An experimental network, consisting of several independent commercial time-sharing computers linked to user terminals through a small communication control computer, was constructed to demonstrate an efficient and flexible approach to remote computer access. The communication control computer, acting as a message handling and translating interface, allowed the use of a uniform terminal control language and common data handling conventions. By linking to the most powerful commercial time-sharing systems available, a reliable medical data processing network was established without a major investment in computer hardware or system software. This experimental work is a major part of the Medical Information Telecommunication Project in the Division of Computer Research and Technology (DCRT) at the National Institutes of Health (NIH).