A field experiment was conducted in Summer-Spring cropping season 2016 at Cujut district, DakNong province, Vietnam  to study the effects of rhizobia and phosphate-solubilizing bacteria (PSB) on soybean (cv. Cujut) cultivated on ferralsols. The experiment consisted of six treatments as follows: control (no fertilizer, no inoculant), 240 kg/ha NPK 15-15- 15, rhizobial inoculant [with liquid cover seeds] + 20 kg N/ha applied at 10 days after sowing [DAS], PSB inoculant [with liquid cover seeds] + 20 kg N/ha at 10 DAS, rhizobial and PSB inoculant [with liquid cover seeds] + 400 kg fertilizer/ha + 20 kg N/ha at 10 DAS and endophytic bacteria inoculant [with liquid cover seeds] + 400 kg fertilizer/ha + 20 kg N/ha at 10 DAS from June to August, 2016. The results showed that application of rhizobial inoculant and/or PSB inoculant produced significantly higher yield component, grain yield than control and did not differ from  240 kg/ha NPK 15-15-15. Consequently, application of rhizobia and PSB improved soil fertility after harversting however using mixture of rhizobia and PSB inoculation plus 400 kg biofertilizer/ha +20 kg N/ha for soybean cultivation supported yield component, grain yield and oil, protein in seed than control and equivalent with treatment of  chemical fertilizer (240 kg/ha NPK 15-15-15). This technique not only increased grain yield, incomes for farmers but also improved soil fertility.