Besides their traditional role as the energy factory of the cell, mitochondria play an important role in other aspects of cardiac cell functioning under physiological and pathological conditions. They are involved in the regulation of calcium homeostasis, production of reactive oxygen species as well as in the process of cardiac cell death. Recently, the interest in their participation in ischemia-reperfusion injury and potential role in cardioprotective mechanisms, with particular attention to developmental aspects has markedly increased.