Cancer cells are defined by their unlimited replicative potential and resistance to cell death stimuli. It is generally considered that a point of no return in apoptotic cell death is the permeabilisation of the mitochondrial membranes. For this reason, agents that permeabilise cancer cell mitochondria have the potential to circumvent their resistance to apoptotic cell death. Fortunately, the proliferative and bioenergetic differences between normal and cancerous cells provide an opportunity to selectively target cancer cell mitochondria.