Abstract: Mitochondria play a major role in apoptosis triggered by many stimuli. The various death signals induce directly and indirectly (through Bcl-2 family proteins) the increase of mitochondrial membrane permeability, the release of cytochrome c and the activation of caspases. The mechanisms that lead to this permeability are not yet completely understood. Here, we review briefly the mechanisms of mitochondrial control during apoptosis and the possible effects of ionizing radiation in their mechanisms.