<p>Brown spot disease caused by <i>Bipolaris</i> spp. is one of the major seed-borne diseases of rice in the world. To find antagonist bacterial isolates suitable for the biological control of this disease, this research studied the effects of three isolates of <i>Pseudomonas fluorescens</i> and one isolate of <i>Pseudomonas putida</i>, <i>Bacillus amyloliquefaciens</i>, <i>Bacillus subtilis</i>, and <i>Pseudomonas aeruginosa</i> against <i>Bipolaris oryzae</i> and <i>B. victoriae</i> in the laboratory using dual culture, volatile metabolites, siderophore, and antibiotics tests. In the greenhouse trials, disease severity, plant height, fresh weight, and dry weight were studied in rice plants that were inoculated with these bacterial isolates and <i>Bipolaris</i> spp. The in vitro tests demonstrated the greatest inhibition of mycelial growth of <i>B. oryzae</i> and <i>B. victoriae</i> with bacterial isolates of <i>P. fluorescens</i> 1 and <i>B. amyloliquefaciens</i> with 67.38% and 71.79% decreases in fungal growth in dual culture tests, respectively; and <i>P. fluorescens</i> 3 with 78.62% and 81.19% decreases in volatile metabolites tests, respectively. These tests also showed that higher Fe⁺⁺⁺ concentrations reduced the efficacy of these bacteria in inhibiting pathogenic fungal growth. In siderophore production tests, <i>P. fluorescens</i> 1 and <i>B. amyloliquefaciens</i> produced maximal inhibitions of 84.61% and 80.76% at 0 μmol Fe⁺⁺⁺ L⁻¹, respectively. <i>B. subtilis</i> produced decreases of 81.65% and 84.23% in antibiotic production tests, respectively. All inoculated bacteria alleviated the severity of the disease caused by the two pathogenic species, and in both cases, <i>P. putida</i> (65.64% reduction of disease severity) was the most effective bacteria. In addition, measurements of traits like rice plant height and fresh and dry weight in the greenhouse indicated that all studied bacterial isolates improved the traits studied of the treated plants.</p>