Two field experiments were conducted during two successive seasons of (2011 and 2012) at the experimental farm, El-Kassasein Research Station, Ismaillia Governorate, Egypt, to investigate the response of garlic plants (Allium sativum L.) to inoculation with Arbuscular mycorrhizal fungi (AMF) and Bacillus megaterium under different phosphorus levels; via., 25, 50, 75 and 100% of recommended dose. The combination treatment (AMF+B. megaterium) showed the highest average bulb weight (g), No. of cloves/bulb, average clove weight (g) and total yield (ton/feddan) under 100% and 75% P compared to other treatments. High contents of N, P, K and total carbohydrates were determined with combination treatment (AMF + B. megaterium) in both seasons, particularly, under phosphorus concentration of 100, 50 and 75%. 100% P + AMF treatment showed higher N% and carbohydrates contents than all other treatments in the first season. Whereas, the combination treatment was higher in nitrogen and carbohydrates contents in the second season. The combination treatment (AMF + B. megaterium) showed considerable increase in plant height at 75% P, while, No. of leaves increased at 50% P. Increasing of neck and bulb diameters (cm), bulbing ratio and total dry weight was estimated at 100% P in both seasons. AMF + B. megaterium + 25% P recorded high values of infection of AM fungi and spores number. High dehydrogenase activity and total count of B. megaterium were recorded with AMF + B. megaterium + 75 or 50% P, after 80 days of planting. Under storage conditions, the least weight loss was recorded with the combination treatment (AMF + B. megaterium) during June where the mean losses in weight percentage during the two seasons were recorded with 100 and 25% P. Whereas, during September, the least weight loss percentage recorded with AMF + B. megaterium + 50% P. The control treatment with different phosphorus levels attained pronounced fungal contamination (Sclerotium, Aspergillus, Fusarium, Pencillum and Botrytis) whereas, the least ones were identified with the treatment AMF + B. megaterium + 75 and 50% P, besides AMF + 50% P (Aspergillus spp.).