Apoptosis is a physiological cell suicide program that is critical for the development and maintenance of healthy tissues. Regulation of programmed cell death allows the organism to control the cell number and the tissue size, and to protect itself from rogue cells that threaten homeostasis. The changed activity of numerous genes influences switching of cells to a self-destruction program. Apoptosis requires co-ordinated action and fine tuning of a set of proteins that are either regulators or executors of the process. Cancer, autoimmune diseases, immunodeficiency disease, reperfusion injury and neurodegenerative disorders are characterised by disregulation of apoptosis. Modulation of the expression and activation of the key molecular components of the apoptotic process has emerged as an attractive therapeutic strategy for many diseases.