Infection with Mycoplasma bovis is an issue of great economic importance to the U.S. cattle industry, causing a loss of millions of dollars each year. This pathogen causes various forms of clinical disease, including pneumonia, arthritis, otitis, keratoconjunctivitis, mastitis, abortion, endometritis, and seminovesiculitis. Basic microbiological information about the organism and the current clinical presentations of M. bovis-associated pneumonia, arthritis, and otitis media are discussed.