Abstract
Phylogenetic relationships among species of the genus Ureaplasma were elucidated by analyzing 16S rRNA sequence information. The 16S rRNA genes of six strains of the mammalian Ureaplasma species were amplified by PCR and were sequenced directly by a primer walking method. The phylogenetic tree based on the nucleotide sequence of the 16S rRNA genes corresponded to the evolutionary history of the host animal species.