Phospholipids are important structural and functional components of all biological membranes. The mitochondrial phospholipid, cardiolipin, comprises approximately 15% of the entire phospholipid mass of the heart. Cardiolipin plays an important role in the regulation of various mitochondrial processes, including ATP generation, apoptosis, electron transport and mitochondrial lipid and protein import. Alterations in the content and fatty acid composition of phospholipids within the heart are linked to sustained differences in myocardial electrical activity. Reduced levels of cardiolipin are an underlying biochemical cause of the Barth syndrome, a rare X-linked genetic disease that is associated with cardiomyopathy and heart failure. This article focuses on the synthesis of cardiolipin, the regulation of cardiolipin synthesis and the implications of heart failure on cardiac cardiolipin and its synthesis.