This proceedings volume contains extended abstracts of papers presented at the 18th Symposium on Operations Research held at the University of Cologne, September 1 - 3, 1993.The contributions were divided into sixteen Theory of Optimization.- Computational Methods of Optimization.- Combinatorial Optimization and Discrete Mathematics.- Scientific Computing.- Decision Theory.- Mathematical Economics and Game Theory.- Banking, Finance, and Insurance.- Econometrics.- Macroeconomics and Economic Theory.- Stochastics.- Production and Logistics.- System and Control Theory.- Routing and Scheduling.- Knowledge Based Systems.- Information Systems and.- Parallel and Distributed Computing.