On 10 October 2007, a Black Vulture (Coragyps atratus) was presented to the Wildlife Center of Virginia, Waynesboro, Virginia, USA, because of an inability to fly. Examination revealed multiple swollen, fluctuant joints. The bird suffered from lead toxicosis and had a prominent leukocytosis. Histopathologic evaluation revealed an acute fibrinoheterophilic polyarthritis, and results of routine aerobic and anaerobic culture of joint fluid were negative, although Mycoplasma sp. sequence-specific polymerase chain reaction was positive. Amplification of a portion of the 16S rRNA and subsequent phylogenetic analysis of the amplicon identified Mycoplasma corogypsi. This is the first report of polyarthritis being diagnosed in association with a Mycoplasma sp. in a vulture species. However, fulfilling Koch's postulates through experimental infections is required to draw conclusions concerning an etiologic diagnosis.