Two hundred and forty bacterial strains were isolated from three potato (Solanum tuberosum) cultivars from eight different sources. On the basis of antagonistic bacteria examination in vitro, greenhouse and field tests, 22.9% of isolated bacteria were endophytic and antagonistic. Three strains, namely A-10', T3 (Bacillus sp.) and H1-6 (Pseudomonas fluorescens), were chosen for their suppressive effect on bacterial ring rot (Clavibacter michiganensis subsp. sepedonicus) and their growth promotion. The strain A-10' was an endophytic bacterium with the effects of colonization, plant growth promotion and suppression of the pathogenic bacteria, showing good prospects for commercial use.