Libraries now have available to them a variety of ways of speeding the flow of information among widely scattered locations. One of the means for the improvement of interlibrary loan service is the use of the teletypewriter, and the use of Teletypewriter Exchange Service (TWX) by medical libraries during the past three years is described. The background of library applications of teletypewriter systems is outlined, and the advantages, types of use, cost factors, and experiences of some groups are discussed, as well as the impact of the "network concept" on library service.