Ca 2 + is one of the key regulators of cell survival, but Ca 2 + can also induce apoptosis in response to a variety of pathological conditions. The pro-apoptotic effects of Ca 2 + are mediated by a diverse range of Ca 2 + -sensitive factors that are compartmentalized in various intracellular organelles including the ER, cytoplasm, and mitochondria. The Ca 2 + dynamics of these organelles appear to be modulated by the apoptosis-regulating Bcl-2 family proteins. In this paper, the recent progress of research on the mechanisms mediating the apoptosis-regulating effects of Ca 2 + and the interactions of Bcl-2 family proteins with the Ca 2 + storage organelles are discussed.