This book constitutes the proceedings of the Fourth International Workshop on Mul timedia Information Systems (MIS'98) held in Istanbul, Turkey in September 1998. This workshop builds upon the success of the three previous workshops in this series that were held in Arlington, VA, West Point, NY, and Como, Italy. As in the past, this is a small focused workshop, consisting of participants drawn from a wide variety of disciplines (e. g. theory, algorithms, real time systems, networks, operating sys tems, graphics and visualization, databases, artificial intelligence, etc. ), all of which focus on research on one or more aspects of multimedia systems. The workshop program included 19 technical papers, three invited talks, and one panel. Of the technical papers 13 were accepted as regular papers and 6 as short con tributions. These papers cover a number of areas including: Multimedia storage system design Image storage and retrieval systems Quality of service considerations Networking support for multimedia information systems Distributed virtual environments Multimedia system architecture issues The invited talks were given by three experts well known for their work in this area. Satish K. Tripathi's (University of California, Riverside) talk was on "Quality of Service Support for Multimedia Data on Internet", Paul Emmerman (US Army Re search Laboratory) discussed "Visualizing the Digital Battlefield", and Val Tannen (University of Pennsylvania) presented "Heterogeneous Data Integration with Mobile Information Manager". The panel discussion, organized by Chahab Nastar of INRIA, France, addressed "Trends in Visual Information Retrieval.