This book collects the Proceedings of a workshop sponsored by the European Molecular Biology Organization (EMBO) entitled "Proteins Involved in DNA Replication" which was held September 19 to 23,1983 at Vitznau, near Lucerne, in Switzerland. The aim of this workshop was to review and discuss the status of our knowledge on the intricate array of enzymes and proteins that allow the replication of the DNA. Since the first discovery of a DNA polymerase in Escherichia coli by Arthur Kornberg twenty eight years ago, a great number of enzymes and other proteins were described that are essential for this process: different DNA polymerases, DNA primases, DNA dependent ATPases, helicases, DNA ligases, DNA topoisomerases, exo- and endonucleases, DNA binding proteins and others. They are required for the initiation of a round of synthesis at each replication origin, for the progress of the growing fork, for the disentanglement of the replication product, or for assuring the fidelity of the replication process. The number, variety and ways in which these proteins interact with DNA and with each other to the achievement of replication and to the maintenance of the physiological structure of the chromosomes is the subject of the contributions collected in this volume. The presentations and discussions during this workshop reinforced the view that DNA replication in vivo can only be achieved through the cooperation of a high number of enzymes, proteins and other cofactors. The need for clean and refined enzymological work, coupled to the contribution of the genetic analysis and molecular cloning, is as pressing as ever in order to obtain a satisfactory picture of the processes at the molecular level. The authors thank all participants for contributing to a friendly and scientifically fruitful meeting. Fifty eight papers were selected to cover some of the most relevant recent approaches and efforts in molecular biology of DNA replication.