This book provides an update on recent advances in the field of ADP­ ribosylation reactions. The individual chapters represent the synopses of contributions which were presented at the Seventh International Symposium on ADP-Ribosylation Reactions, held in Vitznau, Switzer­ land, from September 23 to 27, 1984. This volume covers new developments in the field since the last meeting was held on this topic in 1982, in Tokyo. Therefore, the present text is not meant to form a comprehensive account of a specialized research area, but encompasses a collection of state-of-the-art reports from the vast majority of laboratories currently involved in ADP-ribosylation work. For the sake of rapid publication, the editorial policy was to ensure easy accessibility of information contained in individual articles rather than to provide elaborate cross references or reference to work published prior to 1982. However, a detailed subject index will help the reader find complementary information. The enzymes of ADP-ribose metabolism have not yet acquired universally acceptable trivial names and the Enzyme Commission has not yet defmitely decided on formal appellations. Consequently, a variety of names for the nuclear enzyme appear in this book, including nuc1ear(ADP-ribosyl)transferase, poly(ADP-ribose) polymerase, or synthetase or synthase. Hopefully, a common convention will soon be established. The Seventh International Symposium on ADP-Ribosylation Reac­ tions was only possible because of the generous support which we have been given by our sponsors, listed below.