SARKISSIAN1–3 has reported that partially purified citrate oxaloacetatelyase (CoA–acetylating), EC 4.1.3.7 (citrate synthetase), from bean hypocotyl, pig heart, corn scutella or castor bean endosperm was activated by indoleacetic acid (IAA). Although it was thought that the effect on the enzyme was allosteric, involving sulphydryl groups, Zenk and Nissl4, using a more purified pig heart enzyme, found no activation by IAA at two acetyl–CoA concentrations. In view of these conflicting reports, we have re-examined wrhether or not IAA activates citrate synthetase isolated from plant tissue.