Cardiolipin (CL) is an important component inprokaryotic and in eukaryotic inner mitochondrial membranes. In humans, CL is made by cardiolipin synthase from phosphatidylglycerol and cytidinediphosphate-diacylglycerol. Monolysocardiolipin is an intermediate in CL remodeling, and acetyl transferase tafazzin mutations impairing linoleic acid transfer to MCL are considered the main reason of Barth syndrome. Autoantibodies to CL have been found in patients with anti-phospholipid syndrome and lupus. Trispalmitoyl MCL is a stable, synthetic analog of this rare and interesting phospholipid.