Cardiolipin (CL) is made up of two phosphatidyl moieties linked by a glycerol bridge. It is a tetra-acylated glycerophospholipid playing a crucial role in in both prokaryotic and eukaryotic cells. It is located at membranes associated with the production of an electrochemical gradient assisted in the production of ATP and the transportation of substrates across the cell membrane. CL is abundant in mitochondria of eukaryotic cells, especially the inner membrane of mitochondria. It is necessary for efficient transport of electrons across cytochrome c oxidase by binding this enzyme tightly. Besides, it is also related to the function ATP synthase, the cytochrome bc1 complex and ATP/ADP exchange protein the F0F1. By taking part in cytochrome c release from the mitochondria, CL may play an important role in apoptosis.