Indole-3-acetic acid (IAA) is known for their role in plant root interactions with microbial partners. Current study was focused on role of IAA as signal for colonization between endopytic fungus Fusariun oxysporum wlw and maize roots. Culture filtrate of the strain contained 31 µg/mL of IAA. Addition of tryptophan concentration ranging from 500 to 1000 µg/mL in culture medium significantly enhanced production of IAA by Fusariun oxysporum wlw. The strain effectively colonized the roots of maize and subsequently enhanced the growth and proliferation of host plant. In order to demined the role of IAA in root colonization by F. oxysporum we inhibited the biosynthesis of IAA by using IAA biosynthesis inhibitor which efficiently reduced te colonization of F. oxysporum in maize roots by 46%(foliar application) and 62%(root application) of the seedlings without yucasin (IAA biosynthesis inhibitor) treatment suggesting an IAA crosstalk between the two partners. Exogenous application of IAA restored the ability of endophyte F. oxysporum to colonize maize roots and significantly improved different growth parameters of maize seedlings. It is concluded that a molecular crosstalk of maize roots and endophytic F. oxysporum wlw is necessary for subsequent endophytic association between them.