the inoculation technique with endophytic diazotrophic bacteria in sugarcane has been shown as an alternative practice to plant growth promotion. the aim of this work was to evaluate the biological nitrogen fixation (bnf) contribution by different strains of herbaspirillum seropedicae and gluconacetobacter diazotrophicus in sugarcane plant inoculated from seeds. the seeds were planted in pots filled with non-sterile soil, inoculated with the bacterial strains and grown 10 months outside of the greenhouse. the bnf contribution of the inoculated bacteria varied depending on the plant species used as a control. the highest bnf contribution as well as the highest populations of reisolated bacteria was observed with inoculation of h. seropedicae strains. the roots appeared to be the preferential tissues for the establishment of the inoculated species.