Abstract
The phylogenetic positions of the porcine mycoplasmas Mycoplasma hyosynoviae and Mycoplasma hyopharyngis were determined by using PCR-amplified 16S rRNA gene sequences. M. hyosynoviae is a member of the Mycoplasma hominis group, while M. hyopharyngis belongs to the Mycoplasma fermentans group of mollicutes. Neither species is closely related to previously characterized porcine mycoplasmas belonging to the Mycoplasma hyorhinis group.