The immunopotentiating effect of Phospholipase D (PLD) of Mycobacteria pseudotuberculosis with the Newcastle disease (ND) and Mycoplasma gallisepticum (MG) inactivated oil adjuvant vaccines was investigated by measuring the antibody titers following immunization comparing  the inactivated vaccines alone as control.Two groups of chickens were inoculated with PLD in the 1st group at two weeks before vaccination with ND and  MG inactivated oil adjuvant  vaccines , while in the 2nd group chickens were simultaneously inoculated with PLD at the same time with vaccination against ND and MG. The ND- HI titer was higher in the 1st group (2⁹ )than in the 2nd group (2^8.3)  4-7 weeks postvaccination .In case of MG vaccine primed by PLD 2 weeks before vaccination induced higher and earlier antibodies from the 1st week postvaccination when examined by ELISA test , while inoculation with both MG vaccine and PLD at the same time induced lower titers from the 2nd week postvaccination.The levels of antibody titers in the vaccinated birds and protection level in the challenged birds were enhanced in the presence of PLD inoculated 2 weeks before vaccination. In conclusion PLD was found to be safe and efficacious immune stimulator suitable for use with inactivated vaccines to produce early, better and prolonged immune response.