The invention provides an improved 
Mycoplasma hyopneumoniae bacterin vaccine composition, which advantageously provides 
immunity from infection after a 
single administration. The composition comprises an inactivated 
Mycoplasma hyopneumoniae bacterin and an 
adjuvant mixture, which, in combination, provide 
immunity from 
Mycoplasma hyopneumoniae infection after a 
single administration, and elicit an immune response specific to 
Mycoplasma hyopneumoniae bacterin and including 
cell-mediated 
immunity and local (
secretory IgA) immunity. In a preferred embodiment, the 
adjuvant mixture comprises an 
acrylic acid polymer, most preferably CARBOPOL®, and a mixture of a metabolizable oil such as one or more unsaturated 
terpene hydrocarbons, preferably 
squalene or 
squalane, and a polyoxyethylene-polyoxypropylene block 
copolymer such as PLURONIC®. The vaccine composition may optionally include a 
preservative, preferably thimerosol and / or EDTA. In another embodiment, the invention provides an improved 
Mycoplasma hyopneumoniae bacterin vaccine composition, which advantageously provides immunity from infection after a 
single administration, and comprises an inactivated 
Mycoplasma hyopneumoniae bacterin and an 
adjuvant or adjuvant mixture, which, in combination, provide immunity from Mycoplasma hyopneumoniae infection after a single administration, and elicit an immune response specific to Mycoplasma hyopneumoniae bacterin and including 
cell-mediated immunity and local (
secretory IgA) immunity, in combination with other vaccine components.