Transacetylation of labeled CoA-oleate and oleate into liposomes from dipalmitoyl phosphatidylcholine catalyzed by phospholipase A2 from rat liver mitochondria was studied. It was shown that the efficiency of CoA-oleate incorporation slightly exceeded that of oleic acid both in the phosphatidylcholine and lysophosphatidylcholine fractions. It was found also that some amount of the labeled substrate remains bound to the enzyme; the type of oleate and CoA-oleate binding differs, depending on their concentrations. The autonomy of lipid component formation in mitochondrial membranes is discussed.