Two field experiments were conducted in 2012-2013 and 2013-2014 seasons in Nubaria , Alexandria Governorate to study the effect of seed inoculation and foliar application with Azospirillum and/or Bacillus on growth, yield and quality of sugar beet  fertilized with N (90 kg N/fed) and P (30 kg P₂O₅/fed.). The experiments included 10 treatments with three replicates arranged in a randomized complete block design. Application of both biofertilizers either alone or in combination led to a significant improvement in most sugar beet traits as compared with control (untreated with biofertilizers). Meantime, the response differed according to the kind of biofertilizers. The highest stimulatory effects were exerted in plants treated with the mixture of Azospirillum and Bacillus than either of them alone. This treatment significantly improved growth parameters (root length, root diameter and root fresh weight), root quality (Total Soluble Solids % and sucrose %), nitrogen, phosphorus and potassium contents and increased tops, roots and sugar yields in both seasons. Azospirillum was more effective than Bacillus on growth parameters, root nitrogen and potassium %, tops, roots and sugar yield. But Bacillus was more effective on sucrose % and P% only.    Seed inoculation along with foliar application was the best method on most traits under study. The interactions between biofertilizers and their methods of application led to significant increases in root diameter in the two seasons, root fresh weight, nitrogen, phosphorus and potassium content in the first season, tops yield in the two seasons and root yield in the second season. Therefore, using seed inoculation along with foliar application of the mixture of Azospirillum and Bacillus was the best interaction treatment, which gave the best results and is recommended for beet cultivation in order to minimize soil and water pollution adverse effects. The interaction between both studied factors had a significant effect on all studied characters in the two growing seasons.  Generally, since sugar beet showed in previous studies response to addition reaching go to 90 kg N/fed and attains reaching 30 kg P₂O₅/fed, the use of the two biofertilizers under study might have had complemented the N and P requirements where only 90 kg N/fed and 30 kg P₂O₅ /fed were added.