The aim of this study was to evaluate the antifungal action of ethanolic extracts of avocado seeds, by conducting two experiments in the laboratory of plant pathology of EPAMIG SUL/Lavras, MG, Brazil, in a completely randomized design with three replicates. The first consisted of the following treatments ('Breda' 3%, 'Breda' 2%, 'Margarida' 3%, 'Margarida' 2%, Control, and Ethanol) testing its inhibitory effect on two fungal species (Colletotrichum gloeosporioides and Monilinia fructicola) and the second consisted of different concentrations of extracts (0%, 0.25%, 0.50%, 0.75%, 1.0%, 1.5%, and 2.0%) on the fungus F fructicola. The evaluations were performed at three times (7, 14, and 21 days of incubation) by measurements of the mycelial diameter using a digital caliper. The data were submitted to analysis of variance and the averages were compared by Scott-Knott test at 5% probability. The results demonstrated the positive potential of the ethanolic extracts of avocado seed on the mycelial development of fungi M. fructicola and C. gloeosporioides during the evaluated days.