Plant?microorganism associations have long been studied, but their exploitation in agriculture partially or fully replacing chemical fertilizers is still modest. In this study, we evaluated the combined action of rhizobial and plant growthpromoting rhizobacteria inoculants on the yields of soybean and common bean. Seed inoculation with rhizobia (1.2×106 cells seed?1) was compared to co-inoculation with Azospirillum brasilense in-furrow (different doses) or on seeds (1.2×105 cells seed?1) in nine field experiments. The best in-furrow inoculant dose was 2.5×105 cells of A. brasilense seed?1 for both crops. Inoculation with Bradyrhizobium japonicum increased soybean yield by an average 222 kgha?1 (8.4 %), and co-inoculation with A. brasilense in-furrow by an average 427 kgha?1 (16.1 %); inoculation always improved nodulation. Seed co-inoculation with both microorganisms resulted in a mean yield increase of 420 kgha?1 (14.1 %) in soybean relative to the non-inoculated control. For common bean, seed inoculation with Rhizobium tropici increased yield by 98 kgha?1 (8.3 %), while co-inoculation with A. brasilense in-furrow resulted in the impressive increase of 285 kgha?1 (19.6 %). The cheaper, more sustainable inoculated treatment produced yields equivalent to the more expensive noninoculated + N-fertilizer treatment. The results confirm the feasibility of using rhizobia and azospirilla as inoculants in a broad range of agricultural systems, replacing expensive and environmentally unfriendly N-fertilizers.2013