Mycoplasmas are near ubiquitous causes of disease and economic loss in many livestock species, particularly in intensive agricultural systems. The chronic disease they cause affects animal welfare, increases the likelihood of more severe acute disease after infection with other respiratory pathogens, and drives a considerable proportion of the antimicrobial use in livestock. Although inactivated vaccines against most of the major mycoplasma pathogens have been marketed commercially, there is little evidence of their efficacy. However, there is very good evidence that attenuated live vaccines can be very effective, with their introduction into Australia virtually eliminating the use of macrolides in the poultry industry. The reasons for the superior efficacy of attenuated mycoplasma vaccines are complex, but are at least partially attributable to their capacity to induce effective mucosal immunity and to induce broad immunity against a range of variable cell surface antigens. Our research centre has continued to investigate methods to produce improved mycoplasma vaccines for a range of livestock species over a number of years, focussing on both rationale attenuation and on more empirical vaccine development. This has led to the identification of a number of targets for mutagenesis to develop attenuated vaccine strains, development of improved methods for mutagenesis of mycoplasmas, and the commercialisation of improved live attenuated vaccines, including the first effective vaccine against Mycoplasma gallisepticum for turkeys. These novel vaccines can be expected to have a global impact on the health and productivity of agricultural animals, as well as on public health.