Cardiolipin (CL) is a mitochondrial phospholipid that helps maintain normal structure of the inner mitochondrial membrane and stabilize the protein complexes of the electron transport chain to promote efficient ATP synthesis. Tafazzin, an acyl-transferase, is required for synthesis of the mature form of CL. Mutations in the tafazzin (TAZ) gene are associated with a human disorder known as Barth syndrome. Symptoms of Barth syndrome often include muscle weakness and exercise intolerance. Previous work demonstrates that Drosophila Taz mutants exhibit motor weakness, as measured by reduced flying and climbing abilities. However, Drosophila TAZ mutants' baseline endurance or response to endurance exercise training has not been assessed. Here, we find that TAZ mutants have reduced endurance and do not improve following a stereotypical exercise training paradigm, indicating that loss of TAZ function leads to exercise intolerance in Drosophila. Although cardiac phenotypes are observed in human Barth syndrome patients, TAZ mutants had normal resistance to cardiac pacing. In the future, endurance may be a useful screening tool to identify additional genetic modifiers of tafazzin.