Mitochondria integrate apoptotic signalling by releasing cytochrome c and other proapoptotic cofactors needed for activation of effector caspases. Previously overlooked morphological changes, mitochondrial fragmentation and cristae remodelling, emerged as subroutines of the mitochondrial programme of apoptosis in mammalian cells, as well as in developmental cell death of Caenorhabditis elegans. Mitochondrial morphology results from fusion and fission processes, controlled by a growing set of 'mitochondria-shaping' proteins. Their levels and function appear to influence mitochondrial pathways of cell death, but mechanisms are largely unknown. An emerging model implicates different signals converging on mitochondria-shaping proteins to activate or deactivate them during apoptosis. In turn, these proteins can orchestrate changes in mitochondrial shape to insure cytochrome c release and progression of the apoptotic cascade. These therefore appear an appealing novel therapeutic target to modulate cell death in cancer.