Abstract Changes in the levels of putative free and conjugated indole-3-acetic acid (IAA) were examined by high performance liquid chromatography (HPLC) during the first 96 hr of adventitious root formation in mung bean [Vigna radiata (L.) R. Wilcz. ‘Berken’] stem cuttings. The putative IAA was characterized as biologically and chemically similar to IAA; ester- and amide-conjugated IAA also were found. Amide-conjugated IAA was an order of magnitude more abundant than either free or ester-conjugated IAA, both of which were present at low levels. In duplicate experiments, the relative levels of free and conjugated IAA in the rooting region fluctuated similarly during root formation, although some differences in timing and magnitude were observed.