The Institute of Electrical and Electronics Engineers (IEEE) has been working for several years to develop medical system communication standards, under sponsorship of the Engineering in Medicine and Biology Society (EMBS) The work of the IEEE P1157 Medical Data Interchange committee is surveyed in this paper. By 1990 the IEEE P1157 Medical Data Interchange committee plans to have a draft standard ready for ballot, with an initial focus on the interface transactions needed to support a patient care information system. Eventually, the IEEE P1157 Medical Data Interchange committee will develop standards with a wider scope, including the transfer of electronic medical records between different vendor systems.