Mycoplasma gallisepticum (MG) continues to be an important pathogen of poultry, causing significant production losses in many parts of the world. Eradication is the preferred method of control but it could result impractical after the organism has been introduced in an area with high density of poultry farms. TS-11®, a temperature-sensitive live attenuated MG vaccine, is currently utilized in several countries for the control of MG infections in commercial layers and broiler breeders. In the present field trial, conducted in an industrial meat-turkey farm (belonging to an integrated company), previously affected by severe MG infections, the ability of TS-11® in effectively colonizing the upper respiratory tract in a turkey flock was evaluated (“TS-11®” flock). A second flock grown in an adjacent pen of the same farm was vaccinated with an inactivated MG vaccine (“Inactivated” flock). Polymerase Chain Reaction (PCR) and Random Amplified Polymorphic DNA (RAPD) analysis were applied for the detection and differentiation of TS-11® from other MG strains possibly present in the same flocks, such as the field strains and the 6/85 live vaccine strain currently utilized in commercial layers in Italy. PCR-RAPD results achieved in the “TS-11®“ flock were compared with those of a flock of turkey grown in the same farm but vaccinated with an inactivated MG vaccine. Encouraging results were achieved by means of PCR-RAPD detection of TS-11® from all of the samples up to eight weeks post vaccination, whereas it was never detected in the “Inactivated” flock. Moreover, the field strain was never detected in the “TS-11®“ flock but in the “Inactivated” one it was detected either 5 and 8 weeks after the vaccination. The aggregate production data of the two flocks resulted significantly improved when compared to the performance of the previous flocks grown in the same farm and similar to the production standard of the integrated company.