Many infectious organisms can lead to musculoskeletal symptoms in children. This article reviews recent studies on rheumatic fever, invasive group A streptococcal infections, septic infections of bones and soft tissues, reactive arthritides caused by viruses, fungi or bacteria, and Lyme disease. The search for etiologic organisms in chronic arthritis continues. Although Koch's postulates are not fulfilled in most cases of infectious arthropathies, progress has been made in diagnosing and treating these diseases.