This investigation was carried out at the Agricultural Experimental Farm, Faculty of Agricultural, Al-Azhar University, Assiut, Egypt. Two field experiments were conducted during 2020 and 2021 summer seasons to study the effect of inoculation by bio-fertilizers in order to reducing N fertilization rates of some maize hybrids grown under Assiut governorate conditions. Each experiment was designed in a randomized complete block design (RCBD) in split –split plots design with three replications. The obtained results showed that the plant height, height of the 1^st ear, ear length, number of rows/ear and grain yield (ton/feddan) (feddan = 4200 m² = 0.420 hectares = 1.037 acres) were significantly affected by the maize hybrids, bio-inoculation and N-fertilizer rates, except ear length was not affected by the maize hybrids in both seasons. Results indicated that. Hybrids and bio-fertilizers (H × bio) interaction was significantly difference for all studied traits in both seasons, except for plant height and height of the 1st ear in both seasons. Hybrids and N-fertilizer rates (H × N) interaction was significantly difference for all studied traits in both seasons, except for plant height in both seasons and ear length in only 2020 season. Bio-fertilizers and N-fertilizer rates (Bio × N) interaction was significantly difference for all studied traits in both seasons, except for both plant height and ear height in both seasons and ear length in only 2021 season. Moreover, the results indicated interaction among hybrid type, inoculation with bio-fertilizers and applied nitrogen fertilizer rates (H × Bio × N) was non-significant for most studied traits except for number of rows/ear and grain yield in both seasons.