An attempt was made to evaluate the allelopathic potential of an exotic tree species, Melaleuca leucadendron L. using mung bean (Vigna radiata L.) seeds as responsive bioassay material. This was recorded in terms of the plant extract and plant leachate-induced changes of seed germination behaviour, the levels of DNA and RNA as well as amylase activity in the seed kernels. The results of the present investigation clearly revealed that pretreatment of mung bean seeds with various concentrations [1:1 and 1:2 (w/v)] of M. leucadendron bark extract, leaf extract and leaf leachates for 24 h duration, significantly reduced percentage seed germination and increased the T 50 hours. Levels of DNA and RNA were also significantly reduced with concomitant increase of amylase activity in mung bean seed samples pretreated with the bark extract, leaf extract and leaf leachates of M. leucadendron. Tender bark extract and leaf extract showed more inhibitory action on mung bean seed than leaf leachates. Putative allelochemical-induced inhibitory effect, that is, reduction of seed germinability along with stimulation of amylase activity in seeds, being the important allelopathic indices, it can be concluded that M. leucadendron can potentially render allelopathic action on the experimental bioassay material.