Two field experiments were carried out at Kafr El-Hamam Research Station, Zagazig district, Sharkia Governorate, Agricultural Research Center during 2007/2008 and 2008/2009 seasons to study the effect of biofertilization treatments (control, microbin, rhizobacterin, phosphorin and their interactions) and mineral nitrogen fertilizer levels (0, 40, 80 and 120 kg N/fed) on yield and quality of sugar beet cv. Plino. The main findings of this investigation could be summarized as follows: 1- Application the mixture of Microbeen + Rhizobacterin+ Phosphorien produced the highest values of all studied characters in both growing seasons as compared with using each bio-fertilizer alone. It was followed by application the mixture of Microbeen + Rhizobacterin then application the mixture of Rhizobacterin + Phosphorien in the two growing seasons. 2- Fertilizing sugar beet plants with 120 kg N/fed produced the highest values of root length and diameter, root and foliage fresh weights, TSS %, root and sugar yields/fed in the two seasons. However, the highest means of sucrose % and apparent purity % were resulted from control treatment (0 kg N/fed) in the two growing seasons.  3- The interaction between both studied factors had a significant effect on all studied characters in the two growing seasons. Generally, it could be concluded that application the mixture of Microbeen + Rhizobacterin + Phosphorien as biofertilizers and adding 120 kg N/fed as a mineral fertilization for maximizing sugar beet productivity under the environmental conditions of Zagazig district,.