In order to study the effect of phosphate dissolving bacteria "Bacillus megatherium L." (BM), Azospirillum brasilense (AZB) and Arbuscular Mycorrhiza fungi (AMF) and their mixture treatments on vegetative growth, herb mineral content and volatile oil of rosemary plants (Rosmarinus officinalis), a field experiment was conducted in two successive seasons (2016/2017 and 2017/2018) at private Farm located at Sanuor Village, BaniSuif Governorate, by using a randomized complete block design (RCBD) in simple design. The obtained results referred to that inoculation with Arbuscular Mycorrhiza Fungi (AMF), Bacillus megatherium strain (BM), Azospirillum brasilense strain (AZB) each alone or in mixture significantly increased rosemary growth (plant height, number of shoots/plant as well as herb fresh and dry weights/plant), chemical constituents (total carbohydrates, nitrogen, phosphorus and potassium percentages as well as iron, manganese and zinc as ppm) and volatile oil parameters (volatile oil percentage, volatile oil yield per plant) compared to the control (un inoculated plants). The maximum values in above mentioned parameters were observed in mixed treatment of (AMF+ BM+ AZB) compared to the other ones and control plants. Generally, results of the present work demonstrated that application of biological fertilizers plays a remarkable role in improving growth parameters, chemical constituents and volatile oil of rosemary plants under BeniSuif Governorate conditions.