Book excerpt: Systems Biology of Apoptosis summarizes all current achievements in this emerging field. Apoptosis is a process common to all multicellular organisms. Apoptosis leads to the elimination of cells via a complex but highly defined cellular programme. Defects in the regulation of apoptosis result in serious diseases such as cancer, autoimmunity, AIDS and neurodegeneration. Recently, a substantial step forward in understanding the complex apoptotic pathways has been made by utilising systems biology approaches. Systems biology combines rigorous mathematical modelling with experimental approaches in a closed loop cycle for advancing our knowledge about complex biological processes. In this book, the editor describes the contemporary systems biology studies devoted to apoptotic signaling and focuses on the question how systems biology helps to understand life/death decisions made in the cell and to develop new approaches to rational treatment strategies.