Field studies were carried out at the experimental farm, Faculty of Agriculture, Kafr El-Sheikh University during two successive seasons; 2003/2004 and 2004/2005 to study the effect of mineral fertilizer and bio-fertilizers (Cerealine, Microbien and Phosphorine or mixture of three bio-fertilizers combined with mineral fertilizer) on major insect infestation for sugar beet and growth, yield and quality of  roots. Results showed that mineral fertilizer alone or combined with bio fertilizer highly significant increased the infestation with Pegomyia mixta Vill. compared with control. The highest population densities (1624 indiv. and 135 blotches/48 plants) were in treatment of 90 kg N/fed. followed by Cerealine + 46 kg N/fed. (666 indiv. and 99 blotches/48 plants). Population density of Cassida vittata Vill. highly significant increased on plants treated with biofertilizer plus 23 or 46 kg N/fed. compared with mineral fertilizer alone or control. Mixture of biofertilizers plus 46 kg N/fed. harboured the highest numbers (468 indiv./48 plants) of Cassida vittata Vill. The maximum population density of Scrobipalpa ocellatella Boyd. (73 larvae/48 plants) was recorded in control treatment, followed by biofertilizers plus 23 kg N/fed. While the lowest number of that insect was in treatment of 90 kg N/fed. Population density of jassids, Empoasca spp. highly significant increased on plants treated with mineral fertilizer followed by biofertilizer compared with control. In contrast, population density of Nezara viridula L. highly significant increased in treatments of bio and mineral fertilizer while insignificant at 90 kg N/fed. compared with control. Results showed that biofertilization combined with mineral fertilization highly significant increased root length, root diameter and root & foliage weight of sugar beet plants compared with control treatment. The highest root and foliage weight/plant (938.2 and 198.4g, respectively) were recorded in Cerealine combined with 70 kg N/fed. Phosphorine and Cerealine plus 70 kg N/fed highly significant and significant increased sucrose percentage (20.05 and 18.95%, respectively). Highly significant differences among treatments of mineral and biofertilizer were found for total soluble solids percent (T.S.S.%). Some treatments of bio and mineral fertilizer affected the quality of sugar beet juice such as potassium ions, sodium ions and a amino nitrogen and quality degree percentage. Generally, it is concluded that Phosphorine or Cerealine or mixture plus 70 kg N/fed. are recommended for reducing major insect infestation for sugar beet and increasing root weight and sucrose percentages.