A total of 14 isolates of Staphylococcus aureus and 10 isolates of Staphylococcus cohnii subsp. urealyticum were isolated from 90 field cases of arthritis. Joint lesions that were induced by both staphylococci could not be distinguished and were characterized by fibrinopurulent arthritis and tenosynovitis, associated with synovial cell hyperplasia. Additional changes included chondronecrosis and osteomyelitis. Similar lesions were induced by artificial intravenous inoculation of native colored broilers with the two pathogens. Both species were identified using API Staph kits and detection of 16[Formula: see text]S rRNA genes. Based on a phylogenetic analysis of gap, our isolates of S. cohnii subsp. urealyticum could be divided into two groups. This study is the first report on joint lesions due to S. cohnii subsp. urealyticum infection in broiler chickens.