The present invention relates to a method for the preparation of an immunogenic composition for the treatment and/or prophylaxis of mycoplasma infections in a subject comprising the cultivation of mycoplasma bacteria in a serum-reduced or swine serum-free, eukaryotic cell system； obtaining an antigen of the mycoplasma bacteria； and addition of a pharmaceutically acceptable carrier. Further, the present invention relates to the immunogenic composition obtainable by said method and a method for immunizing a subject comprising the administration of said immunogenic composition to a subject.
