Apoptosis is a form of programmed cell death that is essential for the development and tissue homeostasis in all metazoan animals. Mitochondria play a critical role during apoptosis, since the release of pro-apoptogenic proteins from the organelle is a pivotal event in cell death triggered by many cytotoxic stimuli. A striking morphological change occurring during apoptosis is the disintegration of the semi-reticular mitochondrial network into small punctiform organelles. It is only recently that this event has been shown to require the activity of proteins involved in the physiological processes of mitochondrial fission and fusion. Here, we discuss how this mitochondrial morphological transition occurs during cell death and the role that it may have in apoptosis.