the objective of this work was to evaluate isolates of trichoderma harzianum regarding biocontrol of common bean seed-borne pathogens, plant growth promotion, and rhizosphere competence. five isolates of t. harzianum were evaluated and compared with commercial isolate (ecotrich), carboxin+thiram, and an absolute control. bean seeds of the cultivar jalo precoce, contaminated with aspergillus, cladosporium, and sclerotinia sclerotiorum, were microbiolized with antagonists, and seed health tests were carried out. isolates were evaluated on autoclaved substrate and in field conditions. ten days after sowing (das), plant length was measured. to test rhizosphere competence, isolates were applied in boxes containing autoclaved washed sand, and root colonization was evaluated at 10 das, using five plants per box. the most effective isolates in the seed health tests were: cen287 and cen289 to control aspergillus; the commercial isolate to control cladosporium; and cen287 and cen316 to control s. sclerotiorum. isolates cen289 and cen290 promoted bean growth in greenhouse and field. seed treatment with t. harzianum reduces the incidence of aspergillus, cladosporium, and s. sclerotiorum in 'jalo precoce' common bean seeds.