Proceedings of the 13th International Symposium of The Princess Takamatsu Cancer Research Fund, held in Tokyo The proceedings deal with the potential relevance of ADP-ribosylation reactions in the genesis, prevention and treatment of cancer. These reactions were independently discovered in the laboratories of Paul Mandel, Osamu Hayaishi and Takashi Sugimura, all whom contribute to ADP-Ribosylation, DNA Repair and Cancer. Apart from these renowned scientists, many other outstanding researchers from the international research community have contributed chapters discussing their most recent research results.