Investigators and clinicians researching and applying electrophysiologic phenomena of the eye, met for the XXth Symposium of the International Society for Clinical Electrophysiology of Vision in Iowa City, Iowa, under the auspices of the University of Iowa and supported by the Department of Ophthalmology, headed by Professor Frederick C. Blodi. Two main topics were discussed: I) Electro-oculography and other slow potentials: the phenomenon, origin, analysis, and clinical diagnosis, and 2) Microprocessor applications for computer-assisted recording and analysis of electro visual phenomena. Unusual and challenging diagnostic problems were presented during one evening session. The interest and lively audience participation indicated a need for such an unrehearsed debate. Drs. H.W. Skalka, H. Nakano, H.S. Thompson, A.J. Packer, J.A. Parker, H.E. Kolder, V.M. Hermsen, M.L. Wolf, and Mr. A.1. Mallinson presented case reports and are herewith recognized for their contribution. No documentation is contained in the Proceedings. Several papers were read outside the main topics. Some material appears only as abstract. The highlight of the scientific program proved to be an improvised session on basic mechanisms of slow potentials from the eye. Dr. R.H. Steinberg and his collaborators, together with Dr. G. Niemeyer initiated this part of the program. It was enthusiastically received, provided an informal atmosphere, stimulated a lively discussion and exchanged pro­ found information. A novel feature of this volume is the addition of a cumulative index covering the Proceedings from the last ten ISCERG-ISCEV Symposia. Dr.