The experiment was carried out in the Experimental Farm of Medicinal and Aromatic Plants Research Station, Horticultural Research Institute, in El-Kanater El-Khayria, Kalyobia Governorate, Egypt, during the two successive seasons of 2007 and 2008, to study the effect of nitrogen fixed bacteria (Azotobacter, Azospirillum and Rhizobium) and different levels (zero of NPK, half and full recommended doses) on growth, herb yield and volatile oil yield of Ocimim bacilicum plants. The tallest plants obtained from plants that treated with Azospirillum + Rhizobium + full recommended dose of NPK followed by Azotobacter + Azospirillum alone. While number of branches recorded the highest value from the treatment of Rhizobium + half recommended dose of NPK in the first cut and Rhizobium + full recommended dose of NPK in the second cut. The highest values of fresh and dry weights of herb/plant and total production of fresh and dry weights of herb/plant/season were obtained from Azotobacter + Rhizobium + half recommended dose of NPK in the two cuts of both seasons. The volatile oil percentages based on fresh and dry weights of herb and volatile oil yield of plant per cut and per season recorded the highest values when plants treated with Azospirillum alone. The high concentration from the main component of linalool in the volatile oil obtained from the treatment of Azospirillum alone.