Survey conducted to assess the distribution of soil microorganisms in the Parthenium infested soils of Tamil Nadu revealed that the Parthenium infested soil harboured 13 microorganisms that included Aspergillus niger, A. flavus, A. fumigatus, Chaetomium globosum, Corynespora cassicola, Curvularia lunata, Curvularia sp., Eurotium chavelari, Fusarium oxysporum, F. moniliforme, Monilia sp., Rhizopus stolonifer and Trichoderma harzianum. Among this, A. niger and R. stolonifer were found to be present throughout Tamil Nadu. Both A. flavus and T. harzianum ranked next with an equal distribution of 78.57 per cent. Monilia sp. and C. cassicola represented poor percentage distribution (17.86%) in Tamil Nadu.