Abstract: Bacterial strains of Pseudomonas (Ps1, Ps2, Ps3, Ps4, Ps5) Azotobacter (Ab1, Ab2, Ab4, Ab5, Ab6) and Azospirillum (As2, As4, As5, As6, As8) were used to inoculate the seeds of Helianthus annus var SF-187. Inoculated and non-inoculated seeds were germinated and grown under field conditions until at maturity. Two harvests were taken one after 7 days of germination and other at maturity i.e., after 4 months of sowing. All the bacterial inoculations provoked germination in Helianthus annus. Maximum increase was manifested by Ps5 (223.63%). In general strains of Pseudomonas promoted plant growth more then Azotobacter and Azospirillum, plant height was enhanced by Ab6 (68.66%) and number of leaves was increased by Ps1 (63.63%) after 7 days of germination. However Ps2 strain exhibited maximum enhancement in plant height (57.33%), while Ab1 manifested maximum enhancement in number of leaves (49.01%) after 4 months of sowing. In case of yield parameters As8 manifested maximum increase in number of flowers (128.57%), Ps5 increased diameter of flowers (134.05%), Ab1 weight of seeds (57.00%) and Ab4 (30.35%) manifested enhancement in oil content when compared with control. Biochemical parameters were also increased with bacterial inoculations soluble protein content was enhanced by Ps5 (321.55%), after 7 days of germination and Ab2 (345.45%) after four months of sowing, auxin contents content was enhanced by, Ps1 (1138%) and Ab5 (845.50%), peroxidase activity was enhanced by Ps5 (321.55%) and Ab2 (345.45%) and acid phosphatase activity was increased by Ps1 (97.13%) and As8 (313.33%), after 7 days of germination and after four months of sowing when compared with that of control. These results demonstrate that these strains can be used for enhancing biomass as well as yield parameters.