The fungus Macrophomina phaseolina is a phytopathogen of great importance attacking various crops and causing severe losses especially in sorghum, beans, soybeans and others. Since acetic indole acid (AIA) is a hormone that some authors associate with the pathogenic power of other fungi such as Fusarium oxysporum, it was decided to perform this work to detect whether M phaseolina isolated from beans is layers of producing AIA and which synthesis pathways are involved in its production. The analyses performed using HPLC showed the production of indole acetamide (ACM) that occurs in the first 60 hours of incubation. Another compound produced is Indole (IND) which is released after 60 hours when ACM production has ceased. Similarly, the fungus can metabolize AIA in the culture medium and tryptophan, the main precursor of AIA, apparently has no effect on the amount of AIA synthesized. Conclusion: The phytopathogenic fungus Macrophomina phaseolina can produce indole acetic acid, a hormone that stimulates plant growth through the TRP-D pathway via indole acetamide, which occurs mainly in the first 60 hours of growth of the fungus in the culture medium. In addition, the presence of indole was detected, which allows us to estimate that the fungus uses another little explored route that is TRP-I and that from this compound the AIA can be synthesized directly or transformed into TRP. This means that when a metabolic pathway of IAA is turned off (ACM) it is replaced by another pathway (Indole). The convenient is to correlate the release of indole acetic acid with the pathogenicity of M phaseolina.