This volume contains a selection of manuscripts referring to lectures presented at the Symposium on Operations Research 1999 (SOR'99) held at the Otto-von-Guericke University Magdeburg, Sep­ tember 1 -3, 1999. This international conference took place under the auspices of the German OR society (GOR), and it was the first one organized in Germany since the foundation of GOR by merger of the two predecessor societies (DGOR and GMOOR) in 1998. The Symposium had 420 participants from 22 countries around the world. It attracted academicians and practitioners working in various fields of Operations Research and provided them with the most recent developments and advances in the full spectrum of Operations Research and related areas in economics, mathematics, and computer science. The selection of contributions to SOR'99 accepted by the program committee and the invited pa­ pers formed a program which consisted of 265 lectures in 19 sections, including 2 plenary and 19 semi plenary presentations. 119 manuscripts were submitted for publication in the proceedings vo­ lume. Due to the page limit for this volume and in order to insure a high quality level of the OR Proceedings a further review procedure had to take place which was strongly supported by the sec­ tion chairpersons. It resulted in a selection of 87 manuscripts which are now presented in this volume.