Biofertilization using Azotobacter chroococcum (B1), Azospirillum brasilense (B2) and Bacillus megaterium (B3), were assessed vs. Mineral-N fertilization using ammonium sulphate with 2% 15N atom excess on sunflower grown on a virgin sand during 2014 summer season. Plants grew for 45 days. The highest plant height (64.87 cm) with an increase about 93.6% over the non-fertilized was given by the Azospirillum bacteria combined with the high N rate (N3B2). Total chlorophyll ranged from 17.8% by (N2B1) to 34.9% by (N3B0). The highest dry matter yield of 44.20 kg ha-1 was by N3B0. The highest N uptake was given by plants receiving high N without biofertilization (N3B0) with an increase 141.4%. The highest fertilizer N recovery of 18.45% was by high N without biofertilization (N3B0) with an increase 99.7%.